3bet pot, turn float with 0 equity to bluff river - FPS spew?

[Zeestein]

5/10 WPEX, 4-handed. Nobody doing anything crazy, I've won some small pots without showdown and is the most active on the table. Generally no big confrontations or bluffs.

Weak/tight CO opens (I think like 20vpip 4-handed over about ~100 hands, generally doesn't get involved postflop shenaniggans, he bets and everyone runs for the hills), I 3bet AKo on the button

Flop is J85, all spades. I have no spades. CO pauses then checks, I check behind.

Turn 2 spade, CO pauses and bets 2/3rd pot, I call

River he checks, I bet 2/3rd pot

Basically I think he folds Q flush 100% of the time and K spades like 70% of the time because I think I can't have anything else

[Colombo]

You'd probably be better off just shoving the river instead.