My 71 Roadrunner has power drum brakes and I am running the purple cam 474 lift. You need to check what vacuum you are running as I am, running about 7-8 inches at idle. I works just fine as the engine builds up more vacuum when cruising around town. I had to replace my booster check valve to hold the vacuum when builtup. If you are running much lower that that, you might want to rethink the booster idea. See attached pic, I think the master cylinder is the same.
Ron