Without doubt, flames are THE classic hot rod paint job. I would argue that scallops were here first, but they were never nearly as popular.

I would look for examples of color combinations you like, and look for a painter who's style you like... then let HIM do the job!

Giving a picture of great flames to a guy, who can't seem to get them all pointed in the same direction... or flowing gracefully... will not turn out well.

Do it right, and it is a timeless classic. :-)