Gen III tranny options?

408 swinger said
I would run what you have already, then. Can be built stronger. The 518 is a 4 speed, the 545 is a 5 speed.

I might do that, but first I wanna find out what options I have before I decide.
My tranny man has told me it can pretty easily be beefed up to handle 600 hp but I forgot to ask how much money he needs :)