Cardinal has a good writeup, so read that. I had the same dilemma and used a '75 Corvette manual master designed for 4WDB. I thought I could avoid using a proportioning valve, but thank God I was talked out of it. You should go ahead and install one from get-go. There are a lot of variables you cannot predict and the valve will help you dial in the system. I got mine from Summit and it was about $40. You've got different calipers, rotors and weight distribution between front and rear. No one can predict how the system will work, and you do not want the rears locking up before the front. It actually made installation easier in some respects.