I have a 72 nova, orignal all power drum car, but now it has power disc put on it , I got them from a juck yard and put them on 8 yrs ago when i was working on it. i have just started working on it again. I know that i need to change my proportining valve over , I was going to replace all brake lines in car to with prebent lines , im not sure if i can order brake lines for either orignal power drum or power disc because i never made any modifications to the orignal lines in the car, the only thing i want to change is the proportining valve i need to know if i order a proportining valve for front disk will it work with orignal lines in the car and where can i find on at ???