Heavy Bass Boat metal flake Red. Than introduce the same theme with flames across the hood. You know I could tell you where a really nice pristine classic car is but. Oh never mind.
I would stick with black, just for practicality. But that’s no fun. I like the look of matching the Trucks color. The Truck looks Great, and in a Classy way, because of the grey paint. Therefore, Matching grey frame would look the best. Nice and clean look.
With the color combo you got the first thought that came to mind to me was a Dark Argent Silver. Or maybe do something different like a Hammertone Silver/Grey. Than going along with your wifes idea you could always add some classic accent blue pin stripping to tie it all together.
I got to thinking about the same. A sort of combination of both, maybe a charcoal grey, or high metallic black. Maybe just grey, but a little darker shade. Too dark, it will just look black.
The only way to make it look like a custom black and not the standard vendor black would be to blend in some metallic silver gray to get some depth to it. Or do like @tommymonza said and put in the old school big silver/gold drag boat flakes. What I call shifter ball or bowling ball glitter paint. Lol!