Before I could actually go to plating, I wire-wheeled them to remove surface gunk, put them in an acid metal etch, and gave them a rinse in regular old water.
Actually, it's a nickel acetate solution I made. It's not hard or dangerous - it needs only some vinegar, nickel strips, salt, and low-voltage, low-amperage power - I literally used an old USB wall wart.
Anyway, by hanging the steel parts into the solution, with voltage applied to the nickel strips at the edges and to the parts themselves, nickel gets applied to the steel.
Next up is the accelerator pedal and cable - but that requires more parts needing corrosion protection. And, sadly, my current capacity of nickel plating is not large enough. I need to buy more vinegar, but I am not feeling the need to go to the grocery store on the Tuesday evening before Thanksgiving.