i like the flat on the flop because it is a VERY specific scenario where you're against a bluffy villain, the board doesn't allow for like any hands that would wanna raise here except for sets and overpairs (which as you said he doesn't have), and the board is dry enough so that there are ZERO turns that kill the action.

so yes, flat here, but anyone reading this, understand that this is a very rare spot at the micros.

as for turn, it does somewhat depend on the villain. i don't know how many turns you've seen with this villain or what your image is, but basically if he's a maniac who says "omg overcard to the board on the turn, auto barrel" then obv check.

if he's a maniac (and you have an image) who says "omg no way that K improved his range, his donk is a bluff, auto raise" then obv bet (preferably something that both doesn't look like a value bet, but at the same time a raise commits him to the pot...don't really think that bet sizing exists here so $6 is prolly the best).