600 NL, big draw against floater.

[Grinding2Ecstasy]

This seems pretty reasonable to me, if he's this loose and calls that light on the flop, his range of holdings here contains mostly weak hands and draws which can't call off that kind of money. If he IS stupid enough to stack off with a weak hand you have plenty of equity still. Your line looks very strong though, so I doubt he looks you up light.