I have the same setup and I deleted the proportioning valve. But I do have strange brakes up front. Stock in back. TRZ guys told me to run the fronts right off the master, single line with a T (for both sides obviously) however there a few possible issues you might have- 1. They offer two different masters with two different piston bore sizes(I assume u already knew that) hopefully u have the correct one? 2.master needs to be bled better? 3. Do u have an adjustable rod for the pedal? If so, u may need to lengthen it becuz ur not getting the full throw of the piston inside the master which wont engage the back brakes as good. Also, My 78 wagon had two holes on the brake pedal bar since it came with either power or manual brake option, if u didn't move the rod to the upper hole, u still won't get the full throw which will not engage the back brakes as well either. Just some things to think about, good luck and let us know how u make out!