People under bluff at nl200 in general, and he 3bets you and go bet bet overjam on this board. Sorry I don't believe he will bluff enough on this board with these positions when he overbets river. It's so freakin hard for him to have a Asx-hand that doesn't showdown value and which he decides to play this way. What do you think his bluffs are in this spot?

In theory it's like insane to fold obv, but I would like to think that I could lay down a flush here vs a reg at nl200.. 64/62/63 is a lot of cbetting however so it still feels sick to fold.

I can't endorse folding flushes with a 10:1 stack to pot ratio on the flop.

If villain is a "good" reg, then this is profitable call. If he is a nit, then whatever fold. You have plenty of hands that will want to fold to this allin bet; one pair + spade, two pair and sets are all marginal calls/folds here. Obviously a very profitable bluffing spot for villain if you want to fold the 3rd nut flush. Its actually very easy for him to have a spade in his hand and if he was really "good" he'd realize that people tend to overfold these spots and might have random air.