There are places around that do plasti-chrome resto, but I'd bet the cost would be about the same end cost as a set of Mikey914/914Rubber/Mark W., or even the factory ones (AFAIK they're still available but more than Mark's repros).
I have been able to use some chrome polish to get off grime & the copper oxidation (green crap) that they get on them to some extent, but it's still going to be pitted & imperfect. I got an old pair decent looking for someone once, but wouldn't do that torture again if I can help it!
Since they're a thin plasti-chrome coating over a plastic part (except for the very early pot metal ones 70-71 MY), I suggest the mildest metal polish you can find (some of the brass polish sold in stores like "Pine-Ola" works well) & a soft cloth, combined with lotsa time,
gentle elbow grease (
not as seen on "This Old House"
), & loads of patience .... & eventually they will look a bit better & somewhat shiny again. All a question of cash, time & desired end product!
BTW - it took me awhile, but I finally figured out "Jawja..." - but then sometimes I'm a bit slow!
And still I've been thru Clayton many times on the way between ATL & Cherokee & Asheville NC - go figure!