We ran our World Formula Karts. I'm not sure how fast we where going. It's a 1/7 mile and lap times where in the 12 second range. We just ran our normal setup, but if we go again we should run 17/76 gear to get into our rev limit.
I think it would be way too small for your shifter though. They run an Oval Chassis which is offset, with flat head motors on Methanol. They push about 15HP and run 11" tires on the right side and 4.5" on the left.