Is it possible that your ’63 had factory air conditioning but all the components were removed by the previous owner? I thought you said the ’63 had automatic transmission that was converted to 4-speed manual. Could they possibly have made other modifications you aren’t aware of? All of the A/C components were removed from my car several years ago and you can’t tell that it ever had it except for a couple of extra holes for the A/C lines and some screw holes where the refrigerant lines ran on the inner fenders. The interior controls, ductwork and outlets were hung under the dashboard something like the old aftermarket units did.