[joseki]

What makes turn c/c standard? My impulse is to bet out.

FWIW, I'd fold as played. One thing that makes it hard IMO is the turn check. It plants the seed of weakness in his head, which, I suppose, is why you checked in the first place. But now that you've got him thinking that way, he's pretty much forced to bet the river, regardless of his holding. So, I don't know, he's bluffing here sometimes, but as others have stated, based on combos of a reasonable range that made it to the turn, it's prolly not often enough to call.

My take on his range: 54s, 89s, Axs, 66, 77, 76s, clubs. I'm not sure to what extent, but we have to discount 66/77/76s due to flop call and Axs due to trn+riv bets, right? I guess it could be close.

Also, this deep, how much stock do you place in his preflop action to narrow his range?