284 484 cam and power brakes

I ran the Mopar purple cam 284/484 in my 74 Satellite with a 340, very streetable but my power brakes sucked! Tried the vacumn can, didn't work. I finaly took the power brakes out and went with manual discs, good now! I like the manual brake feel better anyway. I was also running 3.91 gears, 3,500 stall converter, 750 Holley VS, Edelbrock air gap, and Hooker headers on the street. I switched the cam out and went bigger, Mopar's purple 508 lift, still very streetable!