I am in process of converting to front disc brakes on my 1939 Plymouth PT81 pickup. Even after incessant reading about brakes I am still confused about how to properly install valving. I transplanted an 87 Jeep rear along with it's bendix drum brakes and have almost finished converting the front to disc. I replaced the master cylinder with a dual outlet type. Clearly a custom system now, so I believe a factory style combo valve might not the best choice? But to include all the stuff a factory style combo valve does and be able to adjust bias, I would need an adjustable proportioning valve and a metering (hold off) valve and a pressure differential valve (for warning light). I will also need a 10 lb residual check valve. Seems like there should be a simpler way then all these individual valves? Does it make sense to install a combination valve from a similar size vehicle and just add an aftermarket adjustable proportioning valve in case I need to adjust bias on rear brakes? Seems to me this might not work if there is too much restriction to the rear brakes through the factory style combo valve? Am I losing my mind? I was hoping someone made an adjustable combo valve that includes all the functions of the oem factory types. I have not found any? Opinions and advice welcomed.