Power Booster...not sure what I need...

I've been looking at the disc swap...but I've had a very hard time finding the parts or a donor for the swap. Since I'm getting close (hopefully) to getting my car done, I figured that it would be easier, and faster, to simply go with the power booster...especially since I have all my manual brake setup, the setup on a 64 Dart donor car (V8), and the setup on another 64 Valiant 2-door.

I may do the disc swap later on.