Classic Auto Air kit in a 74 Duster.

The big difference in year model is controller head and plenim servos.
Aftermarket is pretty straight forward in cars that didn't come with factory air. When aftermarket is married to or combined with factory a/c components you find the devil in the details. I'm sure the vendor can sort it for you in any a-body.
Personally I'd prefer using all the factory stuff from a donor car to add air except for the big ugly RV2 compumper.