need measurements on remote mirror knob?

Hey guy's I am finishing up my 72 Dart Swinger and I painted my interior door metal black and went to put the mirror on (remote style) and noticed there is not a hole for the remote mirror knob inside!!! lol car was apart when I got it and never checked no real biggie just need to know the measurements where it is suppose to be located so I can break out the holesaw and drill a hole for it! Any help would be appreciated!!