The McLeod twin disk setup is currently looking to be the most promising. There are a couple local guys running them with good results, one is a 900+rwhp LS1 and the other a 600rwhp 97 cobra. Hammer over at modularfords.com is trying a variety of clucthes and is smoking most.
I'll second shadows opinion I ordered mine and will have it soon. Also if youre going to change clutches you should move to a 26 spline input shaft at the same time so you dont have anything else to worry about.