In both Paul’s letters and in how Acts represents Paul, the relationship between Paul and Jesus’s appearance is one of Jesus’ appearing “to” Paul.
This is relevant because it fits well with the context, wherein we understand Paul as saying that through him the Gospel's power is made manifest.
But so what?
Just look at the Greek, the phrase ἐν ἐμοί can only be legitimately translates “in me” (or else, it is by far favored on the basis of the Greek alone). This is relevant because we do not wanting to be violating the rules of Greek.
• NET Bible Translator notes: “Or ‘to me’; the Greek preposition ἐν (en) can mean either, depending on the context.”
Paul was not shy about saying “to” when that was his meaning.
This is relevant because...
- James Dunn: “The ἐν ἐμοί could stand simply for the dative- ‘to me’ - and it is frequently taken in this way. But when Paul wants to use a dative with [apokaluptein] he does so; ... Presumably then the ἐν ἐμοί is chosen deliberately; and the obvious reason is to heighten the subjectivity of the revelation in the moment of encounter and in its impact on his inner life.” [Jesus and the Spirit (Eerdmans, 1975), 105.]