Jack:
The transmission you talk about exists already. Its called a Richmond 5 speed. They have three different first gears, it will handle 600 HP all day long, and is priced ($1,900 in Summit) close to a TKO. I have never understood why so many people use the Tremec. In my opinion, its a piece of $hit compared to the Richmond. If you put any kind of house power to it and hook it up, you will wipe out third gear gaurenteed. Let the 5 liter and SPF boys keep it. My budddy has had a Richmond in his 9.90 second Nova for over 10 years without a problem. By the way, Richmond is the old Doug Nash 5 speed.
Richmond Gears
Jeff