Looking forward to your documentary.
You will luv the brake stopping power improvement.
Just be certain that you have the correct rear drum brake wheel cylinders, because your proportioning valve will only work properly with the correct rear wheel cylinders. You will need the rear wheel cylinders for the factory disc/drum setup, which were used on the 1965-72 8.75" rear with 1.75" rear brake setup, standard on 1968 - 72 factory 340 Abodies.
If you install the wrong rear drum wheel cylinder, what happens is the rear tends to lockup when you apply moderate brake pedal pressure.