Paradox I would suggest that if you go with a 3 drive and I agree they can easily handle 580 Hp . I would not use the merc tranny I believe that repair parts are hard to find . Go with the Borg Warner velvet drive . Great tranny and easily rebuildable .
Cheers RG.

I dont even think the "merc" tranny can be used with a SSM drive. My guess is when he said "merc" tranny, he meant Borg Warner?

I think your right Joe. The Merc trans was for the TRS. The gear in the pump broke if you through much power at it. BW is what you want. The aren't inter changable with out moving the engine foreward about 2"