Interesting subject... what is restored, unrestored or upkept? I wonder if by just using the car and maintaining it, part of the originality is slowly fading away. I personally don’t think so.
What if our car is completely original, but the battery on it has been updated? After all, no one can expect a battery to last for 40 years in a car. What about spark plugs or windshields? Cracking a windshield is a common occurrence, especially back in the 60's (I assume, since I was not even born then), so why should this be a factor to determine originality?
To give you an example, I am a bit of an anorak myself when it comes to maintenance in a car. I had a 92 Alfa SZ (The Monster) which would constantly overflow coolant over the expansion tank on the passenger side of the engine bay... this would end up staining the plastic bottle as well as the paint below. People would agree to consider cleaning the area as maintenance (not repainting to cover the stains), but changing the expansion tank for one that is new and clean may be considered by some as altering the originality of the car... how far should we take this?
All I can say is that it didn't seem to matter when I sold the car, which went back to the original owner who had sold it to me in the first place. I should have learned from that too, as he paid more for it than he had originally sold it to me for...
Anyway. I guess I got carried away. Sorry for the long posting.
Andres G