1965 Valiant brake woes

Have not read every post, but:
- nothing wrong with drum brakes
- if engine note changes with foot on the brake pedal, then the booster is leaking.
- long pedal could just be pushrod adjustment between booster & m/c
- proportioning valve is not usually used on drum/drum brakes. That is because the 'proportioning' was done with the wheel cyl piston diameters. Disc brakes require about 50% more line pressure than drums & with disc/drum brakes that was achieved by using a PV. No need for it with drum/drum & probably hurting braking performance
- brakes pulling; could be sticking wheel cyl, out of round drum, auto adjusters too tight, brake shoes not matched side to side, weak brake shoe return springs etc.