[Bob Kontak]

Welcome!

I like your idea but would default to the thinnest dino oil you can find vs Auto trans fluid - only because there are a lot of additives in ATF that I have not a clue about. Seal swelling agents included.

Can you provide some data about the leak condition before the case clean? Was there seepage or was there a large build up of oil and dirt at the case seam? Given the huge (time) investment to split the case and re-seal, I would live with a bit of seepage.

Additionally, you probably know plenty about these engines, but feeling like butter is not an alternative for pulling a rod and examining a journal/bearing for scoring and using plasti-gage to check clearance. You have to replace the stretch bolts - but for $30 or so it is worth the spend for comfort.