My understanding was the auto crank hole was a larger diameter, but not as deep, and the 4 speed hole was smaller diameter but deep enough to accept the input shaft.
Brewers has the bushing for both scenarios, but they note the bushing for the larger diameter hole in crankshaft is "ideal for 4-speed transmissions that have had input cut off."
http://www.brewersperformance.com/products.asp?cat=32
Mopar Muscle magazine swapped an auto for a 4 speed, and a 5 speed, and noted they used the bigger bushing, but not whether they cut the input shaft or drilled the crank.
This seems to sum it up, scroll down:
http://www.darkside.ca/node/31
I have the same issue I need to resolve asap, and I have the 'auto' crank.
RaniDart70, what size/make drill bit did you use?
How deep did you drill?
Any concerns with the hole not being straight?
I don't want to cut my input shaft, and I want to get this thing back together, so any help is greatly appreciated.