proportioning valve questions

Not sure what kit you bought but you can most likely remove everything from the factory set-up. Does the new one in the kit (under the master) have a warning light switch? If so that is all you will need. But you should check with the manufacturer.

Post #4 shows the distribution block used by the factory which has the warning light switch in it. The prop valve can be seen about 12-14 back from it in the rear line on the frame rail. That is pre-70 factory disc/drum set up. Drum/Drum just used the distribution block and switch.

The newer as shown in post #10 has that separate valve and distribution block/safety switch all built into one unit (combo Valve).

Either of these are not the best design IMO. The adjustable aftermarket units are superior.

Also when a BB is installed, heat from the exhaust can be an issue. The later factory style combo unit will not fit under the factory style shield. So you have to fab one or use the pre-70 pieces.