Dennis, my brake books don't go past 1980, but I would guess that your original system used a combination valve ( more than one function ) for a proportioning valve - and since you are going with the OEM front and rear brakes, I would suggest plumbing in an original porportioning valve, even though your cars weight bias has probably changed some. You can still install an adjustable porportioning valve in the rear line for additional brake bias adjustment if needed. Running the original P valve might not be too important if you are using a trans brake and if you DON'T experence any front tire skidding under light brake applications. Balancing the brake system cam become very "interesting" with a light car and major tire contact differences front to rear.