I have a 1966 Riviera ( not a GS ), the PO had the car lowered by heating the coils until they collapsed. The car looks great, but I can't drive over a speed bump without dragging the frame or exhausts. what was the stock ride height? Maybe a measurement at the rockers? My plan is to buy new springs.
http://www.teambuick.com/reference/library/66_chassis/files/00-a.php This is the best idea of stock height you can get
