Hi,
As a long time painter and artist of some local repute, I gotta say, there was never a car made that won't look cool with some sort of flamejob. Some like it loud and bright, some like if subdued.
You have a very cool car, I like your idea on flat black, ( it looks sinister) and my opinion on flames for your car is....ghosted silver or metallic blue starting at the rear of front wheel wells. Large licks.