I can't speak to your rock guard... but, we just had our baby moons re-chromed. The previous owner had painted them and they were dull even though he used a silver paint and we could still see the rust. We took them to St. Louis Plating and I think they came out pretty darn good for the condition they were in and being from 1959
. Just picked them up yesterday, so no photo yet, but I can get one later today. The places on the moons that were too pitted or rusty are a bit bumpy, but they look 1000% better. We paid $50 a moon and we're extremely pleased. We did price shop and that seems to be the going rate in our area.
If you didn't want them silver, I am sure they could be powder coated too.