Ok guys gimme some direction here. I have a 60's Chevy PU with disc brakes at all 4 corners. They were on it when I got it but no master cylinder or prop valve. It seems to be a myriad of oem parts and some fancy brackets. At any rate, I need them to work, so heres the question....I am going to run a Corvette master cylinder (NON power assist), do I need to invest in the little adjustable proportioning valve for the rear OR will it work just fine with a oem type prop. valve designed for 4 wheel disc brakes? Is there a difference in a proportioning valve for DUAL piston calipers as opposed to SINGLE?