I've recently bled a few old master cylinders, one NOS, the other rebuilt with brass sleeve. Both were a pain. The second one I wound up buying a big hypodermic turkey baster\injector from local hardware store and injected brake fluid in a reverse manner through the brake lines. Method worked great. Air pushed out of piston chamber up into fluid chambers and gone. One that process was complete I set things up like normal brake bleeding to confirm all worked when piston was pushed in.
429rb
429rb