Squeeking brakes on a 75 chevy truck?

if you answered my last question, I had somebody else put it on for me and forgot 2 things, due to in the past the brakes dragging it turned out to be the proportion valve. since then Ive put on new calipers, rubber lines, pads, master cyl, booster, and rotors turned. what can I do to get them to stop squeeking when I hit the brakes?