The fact this this seems like an instacall (but I would get squeamish around AJ) plus he has not played this way before (bigger than normal PFR, silly open shove) sets off my spidey sense.

He's a 46/32, playing 5/10. Unless he's just a gambling lunatic (that you happen to have 500 datamined hands on?). There is no way you can play with those PF numbers without knowning you have a crazy image and using it.

I just have to believe that he thinks you will call with an A. If he's trying to bluff you off an ace here, why bet 10x pot? If you had some kinda TJs/88 hand you might call with PF, why not just bet 360? You still can't call w/out an ace, and he risks 1000 less.

So, I think he has a hand that can stand a call from an ace. I would believe a combo draw, but none is possible. I think he has a 9 or AK or even A9/AA (that 8x PFR is wierd too).

To take it to the next level - this could be a bluff that's never a bluff. So, maybe it's just air.

It boils down to how wierd is is 8x raise. BU *limps* which is weird. Villain raise 8x instead of say 5x. Hero flat calls - with BTN to act (and will be squeeze if BU calls).
I could go either way on that preflop. He could be reading both of you as weak (him for open limping you for just calling) and making a move.