LS1 in 951?

Hello. I'm a newb here. I'm really thinking about getting a 951 to put a LS1 into. I found the kit with mounts at Renegade Hybrids. But I have a quesiton.

Their site says to use the stock trans, and adapt it to the LS1. But I plan on using a blown fully modded LS1 and running 10's in the quarter. So I want to use the manual that comes with the LS1, atleast a beefed up one.

What would I do about the rear diff? Its a IRS right? I know its not strong enough stock. I'm thinking I'd have to throw in a Supra diff or C4/C5 diff. What do you guys think? Is that doable? Has anyone done this swap before?

Thanks guys.