i don't like this at all as its very tough for you to have the Ks.

I also consider folding the turn. I think that the fact that you didn't 3bet the flop would lead me to believe that you thought his range was too strong to do so, therefore I don't see how his range doesn't beat you on the turn.

I think that if you do bluff, it should be for a smaller bet representing thin value with a weak spade.