What to do to make a T1 tranny handle 300 FtLbs of torque?

[Turbo Haraune]

Yes the typ2 box is a strong unit. you want the one with 5 ribs around the diff section. Gear ratios is wrong for racing thou.
The horsepower is no problem for the type1 but the torque is going to snap the half meter long inputshaft with the stupid conection sleeve.
t1 is no good for higher than 7000rpm either. bearings will seize.

I will put my money in a 915 box. expensive to rebuild... yes! but they vil support a 3,6 twin turbo porsche engine!

Also the best you can do for your gearbox is take up all the slack in the system with the cluch before you launch hard...
just grind the cluch a little before you sidestep...