str. and flush draw on the flop

[Your Mom]

2.50/5 6 max at Prima. Villian in this hand is a regular...pretty tight, straightforward player. He probably views me as decent but too loose and too aggressive. I have 500 and he covers. He limps UTG+1. SB completes, I check in the BB with 8s 6s. Flop is 7d 5s 3s. SB checks, I lead for 15, he min raises to 30, SB folds. What's my action?

His hand is either a set or an overpair 88-TT here most of the time. Slight chance of bigger spades or a bigger overpair.