NFD Multiway IP.

the 'but close' bit is entirely reliant on op's read that there are flush draws and gutshots in sb's range and that he stacks off if he hits, but it isn't really that close. Fold.

Also, I can see bb having the non-A sf draw combos in his range too, which juices up our equity. But that's three combos, so it's a small % of his range. There's also tens and jacks on the turn we don't hate, but we're still going to find it tough getting the required implied odds. When we call flop, it looks so much like nut flush draw that I can even see 55 ragefolding at least sometimes when it's losing on river, especially when a naked ace or one spade beats him. I like to be aggressive with my nut flush draws, but that relies on fold equity, which we lack here. So we have to fold because calling or raising is setting money on fire.