I was hoping you'd stick with the original colors (which I really dig), but if you decide to go different, I'll toss out there that 1973 Mach 1's could be ordered from the factory in a color called "Light Pewter Metallic" (color code 5A), which is very similar to the Eleanor gray you mentioned in another post, only better looking in my opinion. Better looking, and factory-correct, you can't go wrong with that.
I used to have a 1973 Mach 1 that was all original, Light Pewter Metallic with Ginger deluxe interior (which is what your car has), and it looked absolutely DYNAMITE. I can highly recommend that combination. My car was a Q-code with power windows, a/c, pretty much every option possible including rear window defroster, and I even had the power driver's seat and power deck lid release (all cribbed from a junkyard Cougar LOL). Sold it years ago unfortunately.
I failed to keep any photos of that '73, but I've attached a photo of my 1971 Cougar XR7 that's the same color, Light Pewter Metallic, just so you can see it...
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