The old style Top loaders work best for this as far as an "economy" transmission goes. If you can find one of the large input shaft trans you can do just a few upgrades ( straight gears, no synchros's) and throw A LOT of power at them. With the right clutch set up ( McLeod Street twin ) they work very well and aren't that hard to street drive. Now if you got loads of money, Jerico ST1200 hands down.