Slant clean-up and oiling question

I am pretty sure the rope seal was original; my '62 FSM describes installing and trimming the rope seal. When it was stopped is a question, but this thread has a post where the poster had torn down his '76 Feather Duster 225 and found a rope seal.... but I can remember getting rope seals in a 383 BB gasket kit in 1980 so that '76's rope seal may not mean anything.
http://www.slantsix.org/forum/viewtopic.php?p=414137&highlight=main+seal#414137

If you ever get the rear cap off, see if the crank has a knurled pattern on it where the rear main seal rides, that was done for the early cranks with the rope seals. I assume it provided 'channels' for the rope seal to work the oil back in.... but that is a guess.

Good to look at the oil pump gear; sounds like you are aware of the later pump gear surface hardness issues. Here is a superb article on that:
http://www.slantsix.org/articles/oil-pump-gear/failure-fix-report.htm

LOL on the drying time.. may I suggest a blow dryer blowing through? Hope your block is clean inside; mine had about 1-1.5 " of plasticene-like 'gunk' in the back of the block (a coagulated mix of old collant residue and rust); pulling the block drain plug resulted in NO coolant flow!!