I wouldn't bother with the older tranny's, never did have good luck making them live. I use an old Doug Nash, full comp version with a Long vertical gate shifter. The comp version was discontinued years ago, still a few around at swap meets and on eBay. Richmond makes a street version of it now rated at about 385 ft. lbs. of torque is all. I ran nothing but top loaders before the Doug Nash trannies came out, always had Liberty gear sets, sliders, and sychros. Did some tricks on the synchros, blocking rings, etc. but that was many years ago and we always took a spare with us cuz things had the tendency to break quite often. With all the good trannies out now, don't think I'd switch to a manual unless you want to part with the big bucks for a Liberty, TKO 600, etc. Going to take some big $$$$$ to buy all the good stuff. If you're intent on doing it, and not spending $6K on a tranny and clutch, I'd suggest digging around to find a few of the old Doug Nash Competition units, put a good one together and keep the other parts for spares....