power boosters are generally really light. I want manual brakes just to save room under the hood and eliminate a vacuum hose.
Do you have a certain year master cylinder that has the groove? Which one did you use?
I actually think some 1980 trucks came with the aluminum master cyl. I know Brian's is for an early eighties truck. I think I have an old one in the shop, if I do I can give you the # to cross reference.