It would be tough for us to appraise the value of your Vette', due to our inability to check through the particular piece in question. If you want the most accurate assessment of your vehicle, I'd recommend looking into getting it appraised by an on-site professional. This way it can be determined the quality of your vehicle, the official designation (ie. restoration, original, and to what degree of either). It sounds like you have a nice piece, but a good appraiser would take a minimum of one hour poking around. I think it would be in your best interest to have it done, as even an appraisal can increase the value of the car (it puts the buyer at ease and more willing to spend the extra bucks). I realize this isn't exactly the answer you're looking for, but it's really all we can do.
I own a 78 myself and I did a lot of shopping before buying it so I saw a lot of prices.
The figures I gave you fall about in the middle. Occasionally you would see someone asking for more but likely wasn't geting it. There are many of them for sale in the $12K to $14K range.
It would take considerable restoration to get in any higher brackets.