A Vette? You mind got warped that day!
Anyway, my steering got tighter and more accurate when I put a strut bar on. Nothing fancy. Just the UMI steel bar.
IIRC, you have the rear suspension replaced already? (LCA's, panhard?)
Ditch the DeCarbons for Koni/KYB.
http://www.stranoparts.com/searchbymodel.php?ModelID=7
Also, look up car builds for autocross, see what theyve done for suspension and do research from there.