Car is up and running well.
Owner is taking it on a 100 mile drive today.
Moral of the story.....Fully clear ALL oil passages in the block of ANY old oil before startup of reassembled engine.
In this case, I left the "block prep" part of the process up to the owner, and he may not have cleared out the inside of the crankcase well after cleaning the block. IDK.....Probably wont' ever fully know.
But for now, everything seems OK to go.