i don't mind to attempt such a bluff but you can't actually represent not a lot of madehand as you would have probably raised with a T or with 2pair or straight on the turn against his draws. but nevertheless you could make him believe to have slowplayed a big hand and i think he could easily fold a lot of better hands like jx Qx and Kx
Flushdraw.
The following range assumed:
K8s, Q8s, J8s-J7s, T6s+, 96s+, 85s+, 75s+, 65s, K8o-K7o, Q8o-Q7o, J8o-J7o, T7o+, 97o+, 86o+, 76o, Kd9h, Kh9d, Kh9s, Kh9c, Ks9h, Kc9h, Kd6h, Kh6d, Kh6s, Kh6c, Ks6h, Kc6h, Kh5d, Kh5c, Ks5h, Kh4d, Kh4c, Ks4h, Qd9h, Qh9d, Qh9s, Qh9c, Qs9h, Qc9h, JdTh, JhTd, JhTs, JhTc, JsTh, JcTh, Jd9h, Jh9d, Jh9s, Jh9c, Js9h, Jc9h, QhTh, JhTh, JcTc, Qh9h, Kh7h, Qh7h, Kh6h, Qh6h, Jh6h, Kh5h, Qh5h, Jh5h, Th5h, Ah4h, Kh4h, Qh4h, Jh4h, Th4h, 5h4h, Kh3h, Ah2h, Kh2h
according to the pokerstrategy equilab the hand distribution tells that he has king high and nothing in around 13% of the times and lowpair or worse in around 27% of the time. so it depends whether he can fold a 7 like 76. i didn't put the a high flushdraws in his range because i think he'd rather play passively and moreover he should have openraised Ax Preflop.
your success rate need to be 25%. without assuming that he is capable of folding pairs the bluff isn'T that good. speculative raise. close but won't cost you that much if you fail and he may believe that you delayed a hand.
are you alright with the range or did i forget any hand that's supposed to be in?
i would actually not fold any pair as you'll have a busted draw yourself often enough but i think it's ok to attempt a bluff and he may have folded a pair.