American Motors: amc V8 timing covers and oil pumps, oil pump housing, low oil pressure

Question

I have a 68 290 CID, a 68 343 CID, and a 69 390 CID engines, as well as an 83 360 CID. When the 360 was in my 83 wagoneer it had low oil pressure when the engine was at normal operating temperature.(dropped to less than 10 PSI) I used 20-50 oil in it and had great pressure during warm up. I attributed this to a warn oil pump housing. Never had any lifter or bearing noises. Is there any way to repair these pumps or must the housing be replaced?

I would like to rebuild all the 60's engines also and have been told these engines need to be externally balanced with the flywheel is this true?

Thank you for your help.
As a young person I worked in an AMC dealership in MA.

Answer
There is no repairing the oil pump on an AMC engine. There is, however, new timing cover housings available from numerous AMC parts vendors online.
You don't need the flywheel to balance it, but if your machine shop can balance it that way, it's OK.