I HAVE A 67 FIREBIRD WITH DISK UP FRONT[4 PISTON CALIPERS]AND DRUM OUT BACK. I JUST PUT ALL NEW BRAKES LINES-CALPERS-ROTORS-NEW POWER BOOSTER[FOR DISK WHICH I DIDNT HAVE BEFORE] -WHEEL CYLINDERS-AND NEW PADS.. MY QUESTON IS WHAT CAN I DO ABOUT THE PROPORTION VALVE AND METERING VALVE?MINE ARE STUCK.AND I CANT FIND A NEW ONE?IS THERE ANYTHING ELES I CAN USE AND HOW DO I HOOK IT UP? THANKS MIKE0861@AOL.COM