Brake Conversion Parts

[Baketown Scotty]

I have disc brakes on the front and am converting to disc brakes in the rear. 1969 K5 Blazer, 10 bolt front, 14 bolt rear. Going to install a master cylinder from 1977 Corvette with dual reservoirs. Since I will have all disc brakes do I still need the proportioning valve with both front and rear feeds from the master cylinder? Or do I do away with the stock proportioning valve and install an adjustable proportioning valve in the rear line only? I guess it could be one or the other? Thanks in advance.