Anyone know how to properly restore cadmium parts.

That goldish plating is kinda like chrome just less expensive. Prevents rust a lot better than zink electroplate seen on hardware store grade.
There are paints from Eastwood and products from Caswell to fake a cadium look on stuff like master cylinder caps but it wont help much on bolt threads since the screwing will probably just peel it off. There are plating companies that plate parts out there. One near me does black oxide, cadium, most everything, but only on new hardware and/or small parts for machine shops. They may require you bead blast your parts clean before shipping.
Try my route, open the phone book and look for a specialty company like Floyds Bolt and Screw (my local find) call them and ask who does cadium plating locally. Good luck