I've seen this add on A/C compressor setup on two 1965 cars, and wanted to upload some pictures to document. The inside evaporator unit was an original 66 model on my car, and looks like an aftermarket on the other.
The compressor is mounted at an angle with a brace coming off the intake to the top. The original alternator bracket is replaced with one with a pulley, and the crank pulley fits inside the original Ford crank pulley.
The alternator bracket pulley lower part has MAPCO stamped on it, and the crank pulley has 11798.
Holes were drilled in the firewall for the lines to the inside unit, and the radiator support for lines to the condenser.