Seems wp. OTR you block his busted fd and he could have floated with some hh combos and got there OTR.

+1 Having a heart OTR is kinda important too.

Question more than anything. Why are we not betting the turn?

Btn doesn't have that many kx. We almost always have best hand and can get value from tx, two FDS, straight draws, maybe even some medium pairs???

Not sure what I would do on river if called. But unlikely a smaller pair/tx would be turning hand into bluff but there's still fd that missed We don't block ax of spades or jqs l for example. I think I would have bet bet, check decided depending on villian and bet size

Preflop is definitely fine

Flop is closer to a c-bet than anything else in my opinion, but you should expect to get called with a pretty high frequency on this texture vs. a standard btn flatting range.

Turn is certainly a bet. We have tons of bluffs that now continue, XXhh, XXss, QJ, 76s/86s/87s, we have so many bluffs to choose from that a very large sizing and a definite bet is ideal. Depending on how many of the above bluff combos you want to be checking back you could definitely have a few bet sizings here for your range. So, developing an overbet for this turn is likely part of an optimal strategy. I'd assume KJ here probably works best as a 80-100% psb however.

River I'd either x/c or bet again myself since again we have so many bluffs. I'd argue this works better as a x/c. But, I wouldn't be folding without reads that villain doesn't bluff much.

More information regarding villain's river tendencies and preflop 3b/flatting tendencies in these positions would be ideal.