Dave,
IMO do yourself a big favor and put your motor on the dyno, and see where the peak torque and HP are. Then you can see what exactly your RPM range for making power is and not be guessing. It will be way cheaper than buying a $5000 transmission especially if you don't need it. Remember that motors will aways pull good in 1st and 2nd as you don't have the drag that you encounter until high gear.
I helped a friend run his lakester back in the mid to late 1980's at El Mirage. It was a real budget car, old rear engine dragster, no covering of the motor, headers stuck well into the breeze, front of the car was covered but no covering of the roll cage and no wind deflector. With a basically stock 327, with a 3/4 grind cam in it, we were able to run a best of 178 at El Mirage on the 1.3 mile course. (if this car had 300 honest HP I would be amazed) For a transmission it had just a two speed lenco with a 1.44 first gear, and as I recall we had 3.08 gears in the rear. The car was driven off the line not pushed.
When I bought the 300 Street Roadster the motor had been blown up at the last meet of the season at El Mirage. I scrounged up some junk parts just to be able to run the car. The motor parts I found were a 350 with 10-1 pistons, cast crank, stock cast pressed pin rods, two bolt main block, stock oil pan and pump, Comp Cams 280 degree hydraulic cam, Early Corvette heads era 1965 with stamped Chevy rockers, the only parts I was able to use off the blown up motor was the single 4 barrel intake manifold with the 650 Holley, and the MSD crank trigger and distributor. Transmission was a turbo 350 that has special kilgore gears in it that are 2.42-1 in first, and 1.42-1 in second. Rear end is a speedway mini quickchange. This car ran a best of 163 mph with that motor at El Mirage, with a 6000 RPM chip in the MSD unit and 2.95 rear end gears. We would go through the lights around 5700 RPM, just where the cam was peaking.
If I had a 900HP motor in my street roadster it would go around 210+ at Bonneville. I am not trying to tell you what to do, only trying to help. Good luck with whatever you do.
Tom G.
