If you are lucky there will be pilot bearing in the rear of your crank already. Not likely.
The hole in the crank is probably there and may already be reamed for a standard bronze pilot bushing. Available at most any parts stores.
If not reamed, you can use the later Magnum bearing already mentioned. Also available at parts stores like NAPA. But you will have to shorten the input shaft by something like 3/8 to 1/2". You can take measurenents and calculate it. No need to disassemble the trans. If it was me I'd use a pneumatic cut-off tool (3"-4" dia) and chamfer the shaft with a file.
