If the point of the site is show off stock colors, then when a car is not "correct", you could add a caption detailing what about the car is incorrect. For example, "1974 XX# (color-code) Frosty Green Challenger Rallye, aftermarket wheels, and added 1971 R/T stripe." That way, people can at least see what the car looks like if they're re-painting the car or considering a color change or just for historical purposes, but with the understanding that the combo they're looking at wouldn't have been available at the time and shouldn't be used as a model for stock restoration purposes.