Kirk,
You ask a very good question. Here is my take on it..
If you are buying the car to be an original and as original as can be and plan to NCRS the car, then the more original and documentation you have the better.
If you plan to make this an investment

Well, from my perspective: I've only made money on 2 Corvettes out of the 9 I've owned. One was a 1954. It was in fair shape when a buddy and I bought it and started a full restoration on it, we had just installed the Blue Flame with a set of side draft carbs and a guy at a Corvette Show offered us three times what we had paid for the car and about twice what we already had in it.. SOLD
The second was a 74 big block that had front end damage and frame damage, we got the frame straightened out and put a used front clip on it and sold it for a couple thousand more than what we paid for it, if we figured in all our time and BEER (back then) we probably broke even
So, it really depends what your intent is. Getting as much documentation on a Corvette is not always the easiest thing in the world to do. You'll read here at CAC about owners trying to trace the history of their cars and previous owners and running into deadends, haveing the documentation is nice, does it make the car worth more ?? I guess in some instances it does, esp. if it is unique to the year e.g. Big Blocks, special options etc..
I'm sure others will chime in with their thoughts.
Bud