You write:
In the surviving works of Irenaeus (175-185), the author of the gospel & 'Revelation' is often called "John, the disciple of the Lord". However, this John is never specified as a son_of_Zebedee/fisherman/Galilean/one_of_the_twelve or even "apostle" (but Peter, Matthew & the twelve are), despite the fact, earlier, Justin Martyr (150-160) stated: 'Trypho', LXXXI "... there was a certain man with us, whose name was John, one of the apostles of Christ, who prophesied, by a revelation that was made to him, that those who believed in our Christ would dwell a thousand years in Jerusalem; and that thereafter the general, and, in short, the eternal resurrection and judgment of all men would likewise take place."
But refer to Irenaeus,
Against Heresies 1.9.2-3:
2 The fallacy, then, of this exposition is manifest. For when John, proclaiming one God, the Almighty, and one Jesus Christ, the Only-begotten, by whom all things were made, declares that this was the Son of God, this the Only-begotten, this the Former of all things, this the true Light who enlighteneth every man this the Creator of the world, this He that came to His own, this He that became flesh and dwelt among us,-these men, by a plausible kind of exposition, perverting these statements, maintain that there was another Monogenes, according to production, whom they also style Arche. They also maintain that there was another Saviour, and another Logos, the son of Monogenes, and another Christ produced for the re-establishment of the Pleroma. Thus it is that, wresting from the truth every one of the expressions which have been cited, and taking a bad advantage of the names, they have transferred them to their own system; so that, according to them, in all these terms John makes no mention of the Lord Jesus Christ. For if he has named the Father, and Charis, and Monogenes, and Aletheia, and Logos, and Zoe, and Anthropos, and Ecclesia, according to their hypothesis, he has, by thus speaking, referred to the primary Ogdoad, in which there was as yet no Jesus, and no Christ, the teacher of John [ἐν ᾗ οὐδέπω Ἰησοῦς οὐδέπω Χριστός, ὁ τοῦ Ἰωάννου διδάσκαλος]. But that the apostle [ὁ ἀπόστολος] did not speak concerning their conjunctions, but concerning our Lord Jesus Christ, whom he also acknowledges as the Word of God, he himself has made evident. For, summing up his statements respecting the Word previously mentioned by him, he further declares, "And the Word was made flesh, and dwelt among us." But, according to their hypothesis, the Word did not become flesh at all, inasmuch as He never went outside of the Pleroma, but that Saviour [became flesh] who was formed by a special dispensation [out of all the Aeons], and was of later date than the Word.
3 Learn then, ye foolish men, that Jesus who suffered for us, and who dwelt among us, is Himself the Word of God. For if any other of the Aeons had become flesh for our salvation, it would have been probable that the apostle [τὸν ἀπόστολον] spoke of another. But if the Word of the Father who descended is the same also that ascended, He, namely, the Only-begotten Son of the only God, who, according to the good pleasure of the Father, became flesh for the sake of men, John [Iohannes] certainly does not speak regarding any other, or concerning any Ogdoad, but respecting our Lord Jesus Christ. For, according to them, the Word did not originally become flesh. For they maintain that the Saviour assumed an animal body, formed in accordance with a special dispensation by an unspeakable providence, so as to become visible and palpable. But flesh is that which was of old formed for Adam by God out of the dust, and it is this that John has declared the Word of God became. Thus is their primary and first-begotten Ogdoad brought to nought. For, since Logos, and Monogenes, and Zoe, and Phoµs, and Sorer, and Christus, and the Son of God, and He who became incarnate for us, have been proved to be one and the same, the Ogdoad which they have built up at once falls to pieces. And when this is destroyed, their whole system sinks into ruin,-a system which they falsely dream into existence, and thus inflict injury on the Scriptures, while they build up their own hypothesis.
Refer also to Irenaeus,
Against Heresies 2.22.5:
5 Now, that the first stage of early life embraces thirty years, and that this extends onwards to the fortieth year, every one will admit; but from the fortieth and fiftieth year a man begins to decline towards old age, which our Lord possessed while He still fulfilled the office of a Teacher, even as the Gospel and all the elders testify, those who were conversant in Asia with John, the disciple of the Lord [Ἰωάννῃ τῷ τοῦ κυρίου], that John conveyed to them that information. And he remained among them up to the times of Trajan. Some of them, moreover, saw not only John, but the other apostles [alios apostolos] also, and heard the very same account from them, and bear testimony as to the [validity of] the statement. Whom then should we rather believe? Whether such men as these, or Ptolemaeus, who never saw the apostles, and who never even in his dreams attained to the slightest trace of an apostle?
Refer also to Irenaeus,
Against Heresies 3.21.3:
3 For the apostles [apostoli], since they are of more ancient date than all these [heretics], agree with this aforesaid translation; and the translation harmonizes with the tradition of the apostles [apostolorum]. For Peter, and John [Iohannes], and Matthew, and Paul, and the rest successively, as well as their followers, did set forth all prophetical [announcements], just as the interpretation of the elders contains them.
It appears that Irenaeus wishes to trace behind each of the four gospels an apostolic origin, and he does so by naming Matthew (of course), Paul (as the apostle behind the gospel of Luke), Peter (as the apostle behind the gospel of Mark), and John (evidently considered an apostle, then). This also seems to be the case in Irenaeus,
Against Heresies 3.11.9:
9 These things being so, all who destroy the form of the Gospel are vain, unlearned, and also audacious; those, [I mean, ] who represent the aspects of the Gospel as being either more in number than as aforesaid, or, on the other hand, fewer. The former class [do so], that they may seem to have discovered more than is of the truth; the latter, that they may set the dispensations of God aside. For Marcion, rejecting the entire Gospel, yea rather, cutting himself off from the Gospel, boasts that he has part in the [blessings of] the Gospel. Others, again (the Montanists), that they may set at nought the gift of the Spirit, which in the latter times has been, by the good pleasure of the Father, poured out upon the human race, do not admit that aspect [of the evangelical dispensation] presented by John's Gospel [Iohannis evangelium], in which the Lord promised that He would send the Paraclete; but set aside at once both the Gospel and the prophetic Spirit. Wretched men indeed! who wish to be pseudo-prophets, forsooth, but who set aside the gift of prophecy from the Church; acting like those (the Encratitae) who, on account of such as come in hypocrisy, hold themselves aloof from the communion of the brethren. We must conclude, moreover, that these men (the Montanists) can not admit the Apostle Paul either. For, in his Epistle to the Corinthians, he speaks expressly of prophetical gifts, and recognises men and women prophesying in the Church. Sinning, therefore, in all these particulars, against the Spirit of God, they fall into the irremissible sin. But those who are from Valentinus, being, on the other hand, altogether reckless, while they put forth their own compositions, boast that they possess more Gospels than there really are. Indeed, they have arrived at such a pitch of audacity, as to entitle their comparatively recent writing "the Gospel of Truth," though it agrees in nothing with the Gospels of the Apostles [apostolorum evangeliis], so that they have really no Gospel which is not full of blasphemy. For if what they have published is the Gospel of truth, and yet is totally unlike those which have been handed down to us from the apostles [apostolis], any who please may learn, as is shown from the Scriptures themselves, that that which has been handed down from the apostles [apostolis] can no longer be reckoned the Gospel of truth. But that these Gospels alone are true and reliable, and admit neither an increase nor diminution of the aforesaid number, I have proved by so many and such [arguments]. For, since God made all things in due proportion and adaptation, it was fit also that the outward aspect of the Gospel should be well arranged and harmonized. The opinion of those men, therefore, who handed the Gospel down to us, having been investigated, from their very fountainheads, let us proceed also to the remaining apostles, and inquire into their doctrine with regard to God; then, in due course we shall listen to the very words of the Lord.
Also, in 3.3.4 Irenaeus recounts the story of how John, the disciple of the Lord, deserted a bathhouse because Cerinthus was there, and then recounts how Polycarp dismissed Marcion with an insult, before summarizing, "Such was the horror which the apostles and their disciples had against holding even verbal communication with any corrupters of the truth." It seems like John is the apostle and Polycarp the disciple of the apostles in this phrase.
Finally, consider Eusebius,
History of the Church 5.24.16 (quoting the epistle of Irenaeus to Victor):
16 And when the blessed Polycarp was at Rome in the time of Anicetus, and they disagreed a little about certain other things, they immediately made peace with one another, not caring to quarrel over this matter. For neither could Anicetus persuade Polycarp not to observe what he had always observed with John the disciple of our Lord [Ἰωάννου τοῦ μαθητοῦ τοῦ κυρίου ἡμῶν], and the other apostles [καὶ τῶν λοιπῶν ἀποστόλων] with whom he had associated; neither could Polycarp persuade Anicetus to observe it as he said that he ought to follow the customs of the presbyters that had preceded him.
So, for Irenaeus, John (the disciple of the Lord and author of the gospel, the apocalypse, and at least two epistles in his name) seems to be an apostle. That said, this still does not necessarily mean that Irenaeus considers him to be the same as the son of Zebedee. Irenaeus also gives the title of apostle to Paul (many times), probably to Barnabas (3.12.14; the online Harvey translation is not perfect here and obscures the matter), and probably also to the seventy from Luke 10.1 (2.21.1). He even calls John the Baptist an apostle in 3.11.4. So the apostles and the twelve are not necessarily identical.
Nevertheless, I think it is inaccurate to say that Irenaeus denies this title to John, the disciple of the Lord.