Anyone sent their gauge cluster to get restored?

I'll admit that I haven't seen it all. I've never seen a speedometer with a plastic bushing in it. Forces applied by the cable is what wears/kills speedometers. When replacing the cable, the square input port should be thoroughly cleaned and cable should be routed into it as straight as possible. That could be all it needs.
Failed mechanical voltage limiter can be replaced with modern solid state regulator from RTE. Any gauge service company would do that. You could do that too.
You said "looking nice" so I'll assume you are referring to the plastic bezel.
Restoring instruments is totally different from restoring bezels. Gauge service companies that do offer bezel restore actually farm that work out to a company that does that kind of service. That's where the extended turn around time comes from. Your ready to go instruments would lay there waiting for the restored bezel to be returned.
I don't know for a fact that Red Line doesn't have equipment to do vacuum metalizing chrome on plastics, does detail painting, everything in house... Maybe they do.
The more common "method to the madness" is or was to send speedometer or whatever instruments need repair to that type business and send the bezel to that type business. Put it all back together at home. Probably the faster and least expensive route. The downside is the limited number of plastics restore services there are today. Fifteen years ago there were at least ten scattered across the country. New reproduction parts, arm rest bases, inst' bezels, etc.. from China, along with EPA regulations put most of them out of business.
I know of one, I wont name here, that does vintage toy restorations and can do instrument bezels and other car parts but.. They wont allow the average joe to send anything auto related to them. They are under contract with one or more of those gauge service companies.
Good luck with it either way you go.