Factory brake booster question

I think the larger can came out in 70, as more cars were coming with disc brakes. I have seen alot of the smaller cans on the 67-69 that had drum brakes. The few that I have, have the gold zinc plating underneath the black paint. If you're building a nice car with nice paint, I would have it plated, for a daily driver regular driver-the black paint would suffice. I am working on a 38 Plymouth, will get power disc brakes. Have a B Body Bendix dual diaphragm that I might use. They were all painted black, If I do use it, it will he gold zinc plated.