No need to bet the turn, the 4 changes nothing and non of their value hands are folding, I'd just be check-calling and hoping to see a cheap/free river. What hands are you trying to fold on the turn? Do you think 7x or 6x or any PP will fold on the 4 of spades? If not, then I don't think we should be betting.

Flop looks like a great spot to check raise with the NFD. You'll have much more success this way than donking the turn on a board where you're raising your strong hands most of the time. As played it's now you who is being viewed as having a capped range because of this.

Once you see the four straight come on the river though I do like that bluff. It should be believable for you to play 65s like this in villain'seyes.