[Radio Wrangler]

Some of the steel treatments of the period you won't be able to get redone, like passivated cadmium plating which was quite common

There seems to have been some sort of corrosion which you want to be sure is gone before adding any coating. So I think I'd start with bead-blasting to get to clean metal.
You could go for painting them yourself, starting with a steel compatible primer.
You could send them off for nickel or chrome plating
You probably have a powder coater near you.Done properly, powder coating comes out like a durable but softish paint. Some powder coating comes out almost like dipping in PVC.

If it was metal finish before, I'd probably go for nickel plating. A recent thread mentioned a firm in Manchester doing anodising (for aluminium) who may be worth asking. You may want a conductive treatment rather than powder coat or paint from the point of view of screening.

David