If I were adding a/c to a non-a/c car I think I would go with a retro air kit of some sort. I do not know if the Cat' stuff will fit into the bird, but you need to get the evaporator core and ductwork up under the dash somehow. The aftermarket kits take care of that for you.
Now - would I do this? That is a personal choice. We have (factory) air in our bird, but it really does not get used much. I have a mixed system in my Plymouth, but do not use that much either. Cruising around town I would rather have the window down and hear the exhaust & music. On long trips it is nice though.
Cal