A/C questions. What to use, what to upgrade?

[Wakko]

I'm trying to get the A/C to work in my '78 Fury and all the parts are there and in good shape.  I originally was going to change the expansion block, receiver drier and clean the oil out of the compressor.  Now that I've got the stuff apart, I'm wondering how long the hoses will hold a charge and I noticed some oil on the compressor (it's the same one that's on the Chargers).  I really want to do this on the cheap, as I want to add Classic Auto Air to my Charger.   I can get a Sanden compressor from a boneyard (with brackets) and have the hoses mated to mine, but is that a pain in the butt?  Should I just stick with what I have?  I don't want to do this twice.