considering his range is mostly mid pps and 10s, i just bet something weak like 10-13 and hope he makes a mistake in calling or gets frisky trying to represent the flush. If he does raise im definitely not folding, just go into check call mode on the river and hope the board pairs. the reason i wouldnt contemplate folding is he could easily be thinking he has the best hand with like a10,33 or is simply turning his hand into a bluff as were deep.