Can't remember seeing a C9ZA-C set of rear springs but we don't often see stripped down Mach I's
According to a March built Mach I with similar equipment as yours (no PS, no AC, 3 speed...) it looks like the stripes were as follows
1 Gold and 1 Brown
Springs would have been marked on the longest leaf just in front of the rear shackle (brown being the one closest to the shackle) with the spring sitting on the eyes of the spring. Stripe typically have been seen only on the (what would become) the bottom of the spring with some paint extending over the edges as the paint was applied. Stripes are typically approx 3/4-1" wide
Hope this helps
To others viewing this thread - DO NOT copy these colors on to your cars springs unless the information about your car matches EXACTLY. Its too common today for judges to deduct for incorrect paint marks and others may see you car, assume they are correct then copy them onto their own cars - continuing the mistake