Depends on how many idiots are in the hand. The flush draw is the scariest and will be around 3-1 to come in by the river (depending on the possibility that a flush draw might also have a straight draw). 660 to you, with the first person behind you needing to call X-80 to win 660+X, so you need X to be 450 to be giving them 3-1 immediately. Of course, you want to take into account implied odds if they hit (and the fact that you really only need to bet around 300 for the first caller to make a mistake on this street). I'd say around 600-700 is probably enough of a mistake to be good.

Except that if idiot caller #1 has top pair and calls, the flush draws start getting priced in by his dead money. Add in the fact that there's at least a 3rd of the deck that's a scare card on the turn and that idiots with flush and straight draws will often make the mistake of calling regardless of your bet (not to mention overpairs), and I think you need to bet more than 700, and you might as well push. Worst case is you fold the draws and pick up a 580 chip profit, but I'd be surprised if you don't get at least one caller.