I bought an aftermarket underdash slimline AC unit for another early A (now long gone!) which would have been no problem fitting with the 65 min-console or the 66-later coffin-style. The unit was self-contained with it’s own evaporator, blower and controls. It would have been easy to install and wire; 2 holes in the firewall for the lines. I will take a couple of pics when I get home