I am restoring a 69RR and I want everything looking new. So what is the best way to clean up the Prop Valve and all the brake parts like it? I would like to flush it if possible and clean up the outside to make it look new. Thanks for the help.

i've used Brass-O on the outside and just a solvent or even gas on the inside.

I clean brass sending units and brake parts with the wire brush on my bench grinder. They come out looking shiney and new. Also clean all the hard ware the same way.
Hard to really clean the insides with out disassembly. I would just flush with brake kleen until the fluid comes out clear. I wouldn't use gas or solvents as it can dry up and leave crud in there.