MC Leaking?

If you don't want to keep fooling with it, and don't care about original look, I would buy a 4-to-2 bolt adapter plate ($30 ebay) and a newer aluminum 2-bolt MC. Many here use an MC from an 80's Dodge truck. I put a 95-99 Breeze ABS MC ($25 new ebay) on the same Bendix booster as yours on my 65 Newport & works great. I forgot if that booster has an adjustable rod into the MC. If so, I adjusted it to minimize "lost motion".