Turn is the easiest double barrel in the world, especially against a fish. You're getting calls from Tx, 33-99, and maybe random overcards.
If you bet the turn, on this river K
I'd probably c/c a smallish bet like 2/3 of pot or below. Probably c/f to a potsmash because the FD got there and fishy players would tend to check back their hands with showdown value ime.