auto crank to 4 speed?

FWIW I used the bigger pilot bearing ( fits the torque converter register ) for my swap and didn't have to shorten the input shaft on my 73 /6.
If you have it apart you should be able to see where the old bearing rode on the input shaft and then can measure the depth of the hole in the crank based on where the bearing would be to see if you'll have to cut the input shaft.