Personally, I think the car should match the cowl tag... Easy for me to say with the 68 cowl tag, I suppose...
But, if you are not matching numbers, then any color/any option should still be at least factory year correct, if we're talking about point judging a car.
BTW, before anyone jumps my case, Maroman asked for my "opinion".
BTW, nowadays, they are called guidelines, not rules.