I have a 67 Chevelle that is basically all original to my knowledge. Last week I went to back it out of the garage and the brake pedal went to the floor. I determined the master cylinder was the problem and pulled it from the car today. I noticed sludge in the bottom of each reservoir and inside of the cylinder when I pulled it apart. I noticed the aluminum pistons were pitted maybe adding to the sludge. What I am concerned with is if this sludge is through the whole brake system. I want to flush the whole system because as far as I know this is the original brake fluid, at least from the 1970’s. I was planning on replacing the brake hoses as well. I am also concerned with are the metal brake lines. They look solid from the outside, however; I don’t know if they are corroded on the inside. Should I flush them with alcohol and blow them out or just replace them? Should I replace/rebuild the wheel cylinders even though they are not leaking? Any suggestions?