Where was the evaporator installed with the dealer installed A/C
I have an aftermarket A/C (Vintage A/C) . The evaporator is installed in front of
the radiator. I am dealing with overheating in traffic. Wonder if my evaporator
is blocking airflow
I am sure the condenser would have been in the front of the radiator because the AC would not work well with the radiator heat flowing through the condenser (not evaporator which is inside the car). You probably need to upgrade the radiator to handle the extra heat load. You may also need a better cooling fan. A fan shroud will give you better air flow through the radiator so if you don't have one I would look into it.
Sorry I failed to address all the things I have done. All those options I have addressed. The only thing I have not done was to locate a smaller pulley for the water pump
You may want an electric fan instead of the old belt driven one. You could install a pusher fan in front if there is room.
If you want more water flow you can get electric water pumps. Speed shops sell them.
No room with A/C Evaporator in front of radiator. No room behind with the nose of the water pump. I order an electric fan with built in shroud from a Falcon catalogue. It was intended for the Mustang that has a larger engine compartment