I'll leave the compressor part up to the experts here, but from my knowledge these units can be restored.
As for restoration options, I know a guy in Gastonia who does some work, his site isn't anything special:
http://antiquesofthepast.comHis name is Ronnie, son's name is Jeff. Might be worth a shot. I can't comment on the quality of his resto work, he didn't have any machines done when I was there.