A/C units I believe are fairly hearty. The only thing they really can't take is low voltage. Most, not all, but most anything else should be OK. If it works, I'd be leaning to getting the shroud.
Plus, if it is working and R-12 A/C unit it will do a better job than a 134a. I know that the 134a works, but coming from the ozone reduction era, R-12 could blow snow out the vents compared with any R-134a system I have.
If it's a non-working R-12 unit, well, then all bets are off unless there is a converison for it. R-12 goes for $800+ a small tankful and you need license, etc to be able to buy, let alone service.