Cooling Issue - 1964 Dart GT - 273 with automatic and A/C

I’ve read somewhere (perhaps on this forum) that the 273 2 barrel in 64 got a smaller radiator than the 22 in ones in 65 and later.. by your dimensions of the aluminum radiator, it sounds like it was comparable with the smaller 64 V8 radiator. Does either radiator cover part of the core support? That might be an issue. I see no shroud which would certainly help.

FWIW your AC appears to be likely Aftermarket installed using a Chrysler compresser. If it were dealer installed they would have mounted the horizontal drier on the top of the passenger inner fender