I was looking at the fragments of Philip of Side, and found myself examining a text of some 40 pages of Greek in E. Bratke, Das sogennante Religionsgesprach am Hof der Sassaniden (TU 19, 3) Leipzig 1899, 153-164 (PDF page 448 f.) An earlier edition of the same text appears in A. Wirth, Aus orientalischen Chroniken, Frankfurt am Main, 1894. Both are online, fortunately for us.
What is this text? Hunting around the web, I find that it is a fictional narrative of a dispute between pagans, Christians and Jews before a fictitious Persian king. The Jews are worsted and convert to Christianity. The pagan leader and “arch-magus”, one Aphroditian or Aphroditianus, points out how the Christ was foretold in pagan books. The latter relates to the presence of collections of sayings by the pagan philosophers (nearly all spurious) in manuscripts of gnomologia in Greek, Syriac and Arabic.
The work is referenced by Shlomo Pines, because it contains a reference to Josephus and the Testimonium Flavianum. I found an article which mentioned it by Alice Whealey, Josephus, Eusebius of Caesarea, and the Testimonium Flavianum, in Josephus und das Neue Testament, Tübingen (2007), p.73 – 116, here.
It doesn’t sound that interesting a work; but I can find no indication that it has ever been translated into English.
UPDATE: A correspondant writes that a modern edition with French translation exists in a recent dissertation: De gestis in Perside : Histoire du texte, édition critique et traduction / par Pauline Bringel ; sous la direction de Jean Gascou (2008). There is information here with a PDF of information about the thesis and the text here. I wonder if it is possible to get hold of a copy!