Bet 500 - if he had a hand he'd have to protect it unless he had the Kc or Qc w/ it (like AK w/ Kc) - if he pushes back then I'm hard pressed to think of a hand I'm ahead of or can outdraw and have to lay it down (if you've seen him pop w/ air then you could factor that in, I assume w/o reads that he hasn't been out of line). Can't see checking as I'm vulnerable and have to call any reasonable turn bet he'd lead with - betting allows me to set the price and may take the pot down right there. If he calls I'll look to check it down.