I'm running a custom 12" single disk kevlar/kevlar clutch provided to me by Bruce Couture at Modern Driveline (
www.moderndriveline.com). Hydraulic master/slave setup with an internal slave (no clutch fork). Pedal effort is less than a stock 5.0L Mustang, can hold 1000hp, and has absolutely perfect street manners. It came all ready to go for the application (385 Series Ford to Dodge Viper T56), along with all the other goodies I needed right down to the special pilot bearing to adapt my industrial 429 crank to the dodge pilot. I'd recommend you talk to those people if you want to do a conversion like this...I couldn't believe how easy Bruce made this happen.
The comment about cruise RPM is very important to think about, as I've found out. Running 3.50 rear gears in my car with a healthy solid-roller cam that peaks way up beyond 7K, I find myself in 4th gear most of the time in slowish CA freeways, and occasionally in 5th...but hardly EVER in 6th; I'd be doing 90+mph on the freeway to get enough rpm to get off the cam lope. The engine doesn't really smooth out until 2400+ rpm. Fantastic for silver-state or land speed racing, but unless you're running a docile cam, the gear spread makes the 2nd overdrive all but unusable. If you lower the rear end ratio, then 1st and 2nd are an even bigger smoke show. I picked 3.50 because I'd finish the 1/4mi in 4th gear (according to the math and assumptions I made). Any lower and I'd be finishing in 5th. I may go to 3.70 now that I've turned the power down some. My traction won't be as bad, and I'll finish the 1/4 at lower speeds now, so I should still finish in 4th. Take the time to do the math and figure out what your cruise rpm needs to be; you'll have a happier combo.