My 73 has the original AC system installed. The PO had recently charged the Freon and I did get some cold air, but not very much. While I like AC, I really don't need it for this car.

I'm getting ready to switch engines, and so I need some advice on what to do with the Freon. Assuming I'm going to remove the compressor and not reinstall it, is it worth it to go to an AC specialist and have them remove the Freon vs. just letting it vent? BTW, I haven't run it (no belt on it right now) since last summer, so I don't know how much, if any, is present.

Also, I know Freon is very expensive. If I take it in to be "captured", is there some way to save it so that if I wanted to reinstall the AC later, I wouldn't have to buy it again?

Don't vent it, that's actually illegal in some states. If it is R12, and it must be unless your 73 has been converted, it is very expensive. Unless you have a leak, it should all still be in the system. It can be captured but you need a tank and someone with the expertise. Call around and see what an a/c specialist would charge to do that. You'll probably have to pay for the tank and his labor but I think the freon is worth keeping.

I might want to buy the AC setup off you =D