[Ronnieroadster]

Originally Posted by Kurt in NJ

the early block has the lower seal as part of the cap, the later is part of the pan
I think it is possible to use the earlier cap and machine it to fit the later bearings, then use a top half of the flywheel housing adapter by adding metal to bolt the pan to but so far i haven’t done close enough measurements and comparison
The crankcase ventilation system would have to be modified too

Some problems with the idea. Besides the rear main bearing cap being different the early rear main bearing design is complexly different between the two types of blocks as well. Next if the early rear main bearing cap was placed on the latter block it would need to be line bored so the center line matched the latter blocks center and front bearing caps.
Now you consider the cost of the line bore operation if a shop could be found to do the job. The cost would easily be way over many hundreds of dollars of what the cost is for the readily available latter oil pan
Ronnieroadster