So far as steel parts are concerned, good-quality chrome plating actually involves three layers: copper, then nickel, then chrome. The combination provides reasonable corrosion protection (mostly due to the copper layer). However I believe it is possible to paint them with lacquer over the chrome to get a further improvement. You could ask a paint expert. So far as the coloured bits are concerned I'd be surprised if the original finish was powder-coated: last I heard they were just spray-painted. Deejay (Darryl) has had some experience with powder-coating some bits of his beloved SB - hopefully he'll chime in with some better information on this option.
