Yeah, just stick it in on the river. You'll get called by Ax everytime, and maybe even Kx if he's really bad.

I don't understand the check behind on the turn. Is it cuz the flop is so dry and if you bet he'll likely fold everything worse than AK?
Yeah, it's almost certainly a wa/wb situation, so there's little danger in giving a free card here. You will induce bluffs from some players, as well as get additional value out of QQ/JJ, which will almost certainly fold if you bet the turn.

Harry: Also consider checking the flop. Doing so would be a better line to induce bluffs from random crap that he called with preflop. The main thing is to just vary your play so you're not predictable.