I've had high success rates of very accurate cable actuated disc brake alignment (with one moving pad) by loosening the bolts just enough so it can move, and then completely removing the cable and placing a business card between the fixed pad and the rotor, and tightening it until everything is snug and then tightening the bolts. This should result in a setup with the rotor just barely clearing the fixed pad, and the moving pad not having to move very far at all to begin contact. Of course, you'll need to straighten the rotor if its bent at all.