Pic below as requested. To my knowledge, the crank is 1968 OE.

Based on the drawing above, I'm starting almost 3/4" short of the minimum 8.75" depth requirement for a stock length input shaft. The overall depth I got was 8.437" measured from the back of the bell to the deepest part of the crank bore. In reality, that depth was even less since you have to subtract some length because the hole becomes conical at the bottom. There's probably a point in every crank where even the stock length/diameter input shaft snout wont fit whether the depth is correct or not. It's tough to discern exactly how much deeper the hole gets after it starts to taper but it's more than .125".

Anyway...

The input shaft on my unit measured 8.625" which is the generally accepted stock length. Add .125" for tip clearance and there's your 8.75" minimum required depth.

So when you convert an automatic car with a crank that's almost .75" shallower than what you need and you're using a bearing rather than a bushing which moves that distance further back towards the trans., you wind up where I'm at having to either drill the crank or cut the shaft. I frankly have no interest in removing the bearing so the shaft goes under the knife.

Could I order a bearing removal tool from Eberg and do it that way? Sure. But hey, I'm lazy and cut corners left and right so buying a tool to properly remove the bearing, waiting three days for it to arrive, chucking it up in the crank and using it, cleaning the grease from everywhere after it's out and then drilling a blind hole for however long it takes to get the depth I need is not happening.