what_a_lovely_sin
Dang kind of a hard choice there. I favor the Stingray but I'd have to repaint it. If it were me, I'd sell the SS convertible and repaint the Stingray.
I'd go for the Sting Ray, if its still sitting in its origional paint I wouldn't touch it! Unless of course the paint is chipping and stuff.
The fewer miles its done and the...how do I put this, the more origional the car is will fetch you a higher price in terms of value. Collectors pay big big money for mint vintage cars. You'd hurt the value of the car by changing it from its origional color.
What you could do though, is if the paint work is fading and all that, re-spray the car in one of its origional color options. In otherwords stick to the colors the car came out with.
Otherwise I'm afraid I don't know enough about American cars to know which one of the two is more valuble. I've always wanted a corvette though.