27K seems like the high end of the Market for the car if it was in the correct colors, and restored somewhat nicely.
It seems to me a 60's Musclecar/ pony car rule of thumb would be the more desirable/sought after the car, the more original paint color plays a factor in the value or in the price they will get for the car.
Of corse it only takes one person (like this Lady) to say they like it and buy it.
Would she still have bought it had she known the tag may not be original to the car and it had the wrong color combo on it, and if it was pointed out this may adversely affect the price when she sells it?
Possibly.
So it seems to me that one person who may buy some of these incorrect cars usually falls into the category of uneducated, or fooled by someone trying to pass the car off as "original".
The 27K is actually the lower end of price manipulation, when you factor in all the guys who change a plain 69 Camaro into a Z/28 or SS. Seems like they easily double the price of the car, and many, many buyers get taken.
Where is this a non-factor? I would say a pro-touring car or "pro street" type of car it probably has no bearing. But even plain jane Camaros if kept all original can command more money in stock appearance.
I have seen a handful of original Camaros painted red, similar to Corvettes painted red, and I think again to the uninformed buyer, it is less of an issue.
I also am somewhat knowledgable about 65-66 Mustangs, and it is a non factor until you get into the more highly optioned cars, like GT or K-codes, for the most part.
So yes, it does affect the value, but there are a pool of buyers who want a certain look, and are less concerned about original color.
Hope this helps.