Scott,
From what I was able to gather springs were natural up until 69 when they changed to black (heat treating?). Totally Auto did my springs and they were finished in a black satin (lower sheen then semi gloss but not quite flat).
Also, I have a few detailing, plating and general finishing articles, similar to what JD was referring to. I'm sure Mike R and others have them also from our earlier days. If they need to be posted again, either here on this thread or in the arc-jives, let me know.
BTW, we expect pics of your efforts from time to time.