I think that the Gospel Peter preached is recorded by Mark.
From the Catholic Encyclopedia:
All early tradition connects the Second Gospel with two names, those of St. Mark and St. Peter, Mark being held to have written what Peter had preached. We have just seen that this was the view of Papias and the elder to whom he refers. Papias wrote not later than about A.D. 130, so that the testimony of the elder probably brings us back to the first century, and shows the SecondGospel known in Asia Minor and attributed to St. Mark at that early time. So Irenæus says: “Mark, the disciple and interpreter of Peter, himself also handed down to us in writing what was preached by Peter” (“Adv. Hær.”, III, i; ibid., x, 6). St. Clement of Alexandria, relying on the authority of “the elder presbyters”, tells us that, when Peter had publicly preached in Rome, many of those who heard him exhorted Mark, as one who had long followed Peter and remembered what he had said, to write it down, and that Mark “composed the Gospel and gave it to those who had asked for it” (Eusebius, “Hist. Eccl.”, VI, xiv). Origen says (ibid., VI, xxv) that Mark wrote as Peter directed him (os Petros huphegesato auto), and Eusebius himself reports the tradition that Peter approved or authorized Mark’s work (“Hist. Eccl.”, II, xv). To these early Eastern witnesses may be added, from the West, the author of the Muratorian Fragment, which in its first line almost certainly refers to Mark’s presence at Peter’s discourses and his composition of the Gospel accordingly (Quibus tamen interfuit et ita posuit); Tertullian, who states: “The Gospel which Mark published (edidit is affirmed to be Peter’s, whose interpreter Mark was” (“Contra Marc.”, IV, v); St. Jerome, who in one place says that Mark wrote a short Gospel at the request of the brethren at Rome, and that Peter authorized it to be read in the Churches (“De Vir. Ill.”, viii), and in another that Mark’s Gospel was composed, Peter narrating and Mark writing (Petro narrante et illo scribente–“Ad Hedib.”, ep. cxx). In every one of these ancient authorities Mark is regarded as the writer of the Gospel, which is looked upon at the same time as having Apostolic authority, because substantially at least it had come from St. Peter. In the light of this traditional connexion of he Gospel with St. Peter, there can be no doubt that it is to it St. Justin Martyr, writing in the middle of the second century, refers (“Dial.”, 106), when he sags that Christ gave the title of “Boanerges” to the sons of Zebedee (a fact mentioned in the New Testament only in Mark 3:17), and that this is written in the “memoirs” of Peter (en tois apopnemaneumasin autou–after he had just named Peter). Though St. Justin does not name Mark as the writer of the memoirs, the fact that his disciple Tatian used our present Mark, including even the last twelve verses, in the composition of the “Diatessaron”, makes it practically certain that St. Justin knew our present Second Gospel, and like the other Fathers connected it with St. Peter.