I have a 1974 chevy C10 stepside. Rear brakes were locking in "quick" stops so I just changed the 48 year old proportioning valve as the rest of the brakes were done about 2000 miles ago. EVERYTHING but the lines is new. And some of the lines are new. Anyway, in the process I inadvertently knocked my temporary plug out of the line and I lost all of the fluid in the front brake reservoir, (the little one to the rear of the truck). I am about to bleed the brakes with a pressure bleeder. Do I need to re bench bleed the master cylinder since one of the chambers siphoned dry?? Thanks for your help!