I'm working on designing a fixture to put a neoprene seal on a GMC block, but it will require some machining on the block and the rear main bearing cap. It looks like the shop that ground the crankshaft made a serious error when centering it in their equipment. The seal surface definitely needs to be concentric with the bearings, even if it's slightly undersize. Have you checked on the indexing of the rod journals? They might also have issues. Best Gasket makes a very good quality rope seal that can handle an undersize seal surface. Do you have a 4 or 6 bolt flywheel flange?

Drop me a PM message- - - -I have a suggestion for a fix that might need to be discussed by phone.
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!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!