In my humble opinion:
You're UTG so you have a limited range. He is likely to expect you to be on that exact hand or another 1 pair hand. His overbet push is probably intended to look bluffy.
I think he wants you to think he turned a combo draw. Although, I don't think he thinks he has fold equity by pushing vs your range with your history, so he must be looking to get paid. If he really turned a combo draw he'd call with position. Therefore I think he's likely on 2 pair or possibly a set b/c he may not 3bet your UTG raises w/ mid PPs.