For the really nasty chains, i think the first step will be the wire wheel on my bench grinder. Then maybe I'll get a gallon of that Super Clean for the rest of the corrosion and see how it comes out . If the chrome is gone from the cutters, does that mean it's junk?
Can't recommend the wire wheel - too aggressive, and may scratch or damage the good parts of the chain. Also, it may rip the chain out of your hands! A more 'gentle' way is to drive a screw or nail into a scrap board (or work bench) so that you can stretch the loop out a bit, and hit it with a stiff brush to knock the loose stuff off. I like the fine wire, stainless steel, 'scratch brushes' (third from the right in photo below) sold by welding supply store for TIG welding. Under $1 each here, and much better than the junk ones (2 at far
left) that sell for more at the home centers.
Super Clean is a water based degreaser (containing 'lye' -sodium hydroxide); it will not remove rust, but will remove the grease, allowing the rust removing chemicals to reach the remaining corrosion. Light surface rust is usually not a problem. Deep, pitted rust damages the underlying metal.
See what works for you, and please post your results here for others.
The chrome protects the cutter from abrasion. Once its gone, the cutter can still cut, but will be subject to faster wear. Apparently, some race chain makers actually remove the chrome intentionally (?). Again, experiment with these chains to see what you learn. Then make choices about which ones are worth saving. Some of those look like cool, older chains. Some of those cutters will also need a lot of attention, once the rust is cleaned up.
Philbert