Re: which bridge???
Its an Edge III you have on there right now. You can typically replace those with an edge pro with no modifications.
That said, don't limit yourself. The modifications for getting any floating tremolo to fit in there are relatively minimal - you're talking a few mm of wood different between getting an OFR, Edge, Edge Pro, LoPro, Gotoh GE1996t, or even a Floyd Rose Special.
If you're willing to make that kind of modification to an instrument, its always worth doing it right - halfway houses are the kind you wanna move out of real fast.