As per the standard accounts that I have looked at, these types of relative clauses don’t exist in Koine Greek. The vast majority of relative clauses in Greek are post-nominal (they follow their antecedent), with a minority being internally headed (their antecedent is incorporated within the relative clause; Smyth discusses these under the name “incorporation”). In the NT, this is ~95% to ~5%, as per both Culy and Hayes (Culy, Martin M. “A Typology of Koine Relative Clauses.” Work Papers of the Summer Institute of Linguistics, University of North Dakota Session 33, no. 3 (1989): 67–92; Hayes, Michael. “An Analysis of the Attributive Participle and the Relative Clause in the Greek New Testament.” Doctor of Philosophy, Concordia Seminary, 2014).ἀποσυλήσαντός μου ἤδη ἅπερ ἦν ἠμφιεσμένη ἐντάφια,
“and I had already stripped off the grave-clothes in which she was clothed” (trans. from Schneemelcher NT apocrypha vol. 2)
It would seem that this relative clause in Acts of John comes before its "antecedent," and that the "antecedent" is not part of the relative clause, thus not an internally-headed relative clause.
So, I guess my question is in two parts:
1. I would call this a prenominal relative clause, not an internally headed (aka incorporated) one. Would anyone else consider that a valid understanding?
2. Does anyone know any grammar which discusses this possibility and offers any other possible examples?
P.S. I've taken the language of internally-headed relative clause from Culy. He does not really explain it or justify the application of the title to the phenomenon in Greek, beyond saying, "[the phenomenon of incorporation] corresponds to the linguistic notion of an internally-headed relative clause." Stefanie Fauconnier has justified this approach in a recent article I found useful: “Internal and External Relative Clauses in Ancient Greek.” Journal of Greek Linguistics 14, no. 2 (2014): 141–62.