OK, this started out with PaulR asking about 280SL hubcaps. To the best of my knowledge:
Early/original 14" one piece wheel covers (wasn't it only 230/250 that had two-piece?) were chrome plated steel.
Later and or new OEM are highly polished stainless steel.
I don't think they are available any longer; I think MB had a batch made some years ago, and these have been sold out. Since this 14" model appeared on many cars, my guess is eventually they'll make more?
I believe there are some reproductions floating around out there, new...check all the usual suppliers.
I think it would be very costly indeed to repair severely scraped up covers. Any imperfection in a high-gloss chrome plate will look dreadful. Perhaps a master metal worker can do it, but his is going to cost a lot of money, because you are paying for skill and time...better have it perfect prior to re-plating.
Personally, I'd go with what is available, pay to have them buffed/polished to a super finish, and repaint. Forget the old ones.