I need brake parts!

All you really need is the push rod, which I have. PM me for info. If you are just going from power to manual but keeping the same brake type (disc or drum ) and you have a good master cylinder you don't need a new one. You're right that you can get a rebuilt master cyl locally for not too much money - a 73 and up one will work on 72 and back. All you need is to remove the booster and linkage to the pedal and replace the push rod and you can reuse your existing master cylinder. Just re-bend the brake lines to meet the new location of the master, or bend and flare up some new ones.