If your Vette is really close to stock, you might want to look at the rules for IHRA Pure Stock.
You should be able to run the index in that class. The rules are more strict, but the indexes might be easier to obtain.
The link below is to the IHRA Competition page. Scroll down to the bottom to "Rulebook" and download.
Good luck on your project.
http://www.ihra.com/competition/index.php