Proportioning valve options with disk brake conversion.

The 73-up disc/drum distribution block includes a proportioning valve... HOWEVER, when I tried to use that on my slant six to disc conversion, it had way too much rear bias. So I wound up adding a Summit adjustable proportioning valve. You can install this WITHOUT cutting or bending any lines. Here is how you do it:
1. Buy a short piece of premade brake line form O'Reilly's or whoever — something around 16-20 inches should do it.
2. Bend this into a circle with a tubing bender, so that the two ends are next to each other.
3. Undo the line at the distribution block that goes to the rear brakes. Attach one end of the loop instead.
4. The other end of the loop goes into the input end of the new proportioning valve.
5. Connect the output of the proportioning valve to the rear brake line.

The purpose of the large loop is to provide enough flexibility so that you can locate the new proportioning valve directly beside the distribution block, so that the rear brake line only has to flex a few degrees to one side — you don't even have to put a hard bend into it. My block had a handy protruding bracket that I just attached the PV to, with the adjusting knob pointing up. Mounted low like this, it isn't super obvious lookin into the engine compartment, but it is easily reached for adjusting.

In my case, I had to turn the rear bias down to only about 20-25% (3/4 of the way from full rear bias).

In case I didn't make it clear, you can do this same installation using the stock drum brake distribution block, if that's what you have.