Well, I'll tell you what I am in the position of. I have a survivor 67 L35 I bought in 1980..original paint, original motor and drive train, spark plug wires dated 1972 (real, not repos), original glass, etc....
Just to name a few areas needing attention:
The windshield lamination has separated a lot around the edges
The trunk, header and roof top paint (all horizontal surfaces actually) has dried a lot, spider crazed, faded and some minor oxidation has started. No buffing will take this out.
A few very minor door dings that stand out being the car is a dark color.
Chassis surface oxidation in several areas
Rims need a repaint
Battery tray that is beyond rotted
Dinged and pitted fender well and RS rocker trims
I have to draw a line somewhere when to stop worrying about being original once and restoring the whole car otherwise one can be displaying an original 'sh*tty' looking car. Sure, many like to see original paint, etc but for a very well preserved car, that is easy to do. But, like being original only once, I'm living a life only once so I want to do what I want to do and not necessarily what others say I should do. Looking at resale prices, I don't see enough true survivors to say that they really command the higher resale price. As with anything, a price of worth is what someone will pay for it and from what I have seen thus far people will pay good money for a well restored car vs. an original that is not at the same "pretty" level. I don't sell my cars anyhow but do want to drive them before passing them on to my kids.
This is just me and my opinion and I have struggled a lot with the decision of "to restore, or not to restore" but each time I look at the dead paint and oxidation that is starting, I don't want to let rust take over for the sake of being original.