Effective stacks 1700

Fish(500) raises $30
Good reg Btn raises $100
Hero SB raises $345 7c9c8hTh
Fish folds
Btn calls

Flop AhJhTc (730)

Bet pot? Bet $450? Check call? I don't know what to expect of this villain if I check on this board. I can't see him stabbing incredibly light. He can 3bet the fish with a lot of broadway hands QQ+ and some rundowns