Wouldn't the smaller register affect a manual trans only since the bore is for the pilot bushing? How does it affect the torque converter? I'm stupid...
the convertor snout sits in the register on the back of the crank and 67 & earlier have a small convertor [fewer splines also] snout and small crank registers while 68 & up are big.
You can grind it out bigger even by hand you mic the amount you remove as you go, or machine shop time.
The outter's are the same with v8's, so no flywheel issue.
The input pilot's are all the same.