You...........don't..........need.........a booster
I'm using factory 73/ 74 K/ disk/ spindles up front, and a Linc/ Ford Versailles 9" in rear. I just ruptured the residual valves and used the stock 67 factory non boost master. I'm 70 and have arthritic like issues. I can lock it up on the freeway
What you MAY need is a smaller bore master
