Update, I was able to find on eBay an NOS MC for disc/drum. Also made sure that it didn’t need rebuilding being that it is NOS. Seller said that all of the rubber is checked before shipping so rebuilding wouldn’t be necessary. I installed it and the brakes work as they should. It was the MC all along. I still have minor adjustments to the shoes in the rear but overall a major improvement. Thank you for all of your input and advice.