63 Signet Drivers Mirror Replacement

I wondering if the previous owner had the early mirror, removed the cables from the control, fed the cables through the mounting bolt hole, and just held the mirror on with the rear screw. ?? I think you just need to drill a hole big enough for the control of the late mirror you have. It will be under the mirror base, so it won't show. I have the later style mirror on both my 63 Valiant and on my 65 Barracuda, so it can be done.