[Painter D]

i have the exact same setup as you do. same motor, trans, brakes setup etc.. i also had this same problem with mine. so heres my first question ,you said you had a new proportioning valve, is it an adjustable, or the factory style. by , (factory) i mean a disc front ,drum rear valve. i replaced the factory style first and it did nothing , however i put the adjustable one on and it fixed it. i also had a new master cylinder and it turned out to be bad i had to get another one. hope this helps