Vil is 19/13 over 86 and seems to be a bit on the tighter side, not too much though

Preflop: Think its a fine 3b, there may be arguments to cut it down maybe to KTs+ since hes a tiny bit tighter, but dont think it matters too much

Flop: Standard cbet and he calls. He can have all the Qx, PPs below Q, dont give him too many 4x (54s, A4s maybe). Floats with A high (AJ-AQ) are definitely also possible with some BD-straight draws (JTs, KTs, KJs).

Turn: Once I bet here I basically made my decision already to turn it into three streets. We would fold out here overcard hands he called or bd-straight draws, but I think his PPs are not going to find a fold just yet. Also I think enough players still call here with A high.
An argument to continue bluffing K9s here is that we unblock his overcard+BD FD floats that now fold OTT.

River: I think in such scenarios the higher the river card, the better it is for us, since his PPs will be perceived weaker from the board texture. As a river bluff the 9 might not be ideal due to unblocking his folding hands, but seeing that we can fold out a bunch of his holdings (55-77), block potential full houses (KQo and KQs), I think its profitable enough to jam it.