I don't believe it's that critical. I seem to remember that the bellhousing was dial-indicated concentric with the block on the Hydramatic engines to minimize runout, but unless there's a difference in the crankshaft hub, the cranks should interchange between standard and automatic engines without a problem. There have been a lot of bellhousing/block swaps done over the past 60 years, too, I'll bet!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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