Putting A/C in a formerly-A/C car

Title says most of it...late (74-6) Duster, factory A/C car, pretty much everything except the under-dash unit is gone. In a perfect world, I would prefer the factory system...but I know that hunting down everything needed would be very difficult, probably expensive, and take forever. But...will any of the aftermarket units (Vintage Air, Classic Auto Air, others?) work in a factory A/C car?