I upgraded from power drum to factory power disc on my 67 skylark. I moved the proportioning valve up onto the booster and removed the hold off valve on the frame. I replaced all of the brake lines. They leak. Can over tightening a steel brake line into a brass prop valve damage the inverted flare in the valve? I leave it over night and come in the next day and it has a drop hanging on the line. It's just the front that is giving me fits.