I had a body man tell me one time the fiberglass bodies can be a nightmare with age. Here's a quote from Hemmings:
"Body Corvettes were among the first production automobiles to use reinforced fiberglass bodies, and they have a reputation for remaining rust- and dent-free virtually forever. But unlike steel panels that bolt on, working with damaged fiberglass requires special skills. Carefully inspect a car's body for wavy bodywork, uneven panel gaps or overspray on trim. A good tip for checking front body alignment is to line up the nose center point with the roof's center T-top seam, and if it is off, something is awry. Check the fiberglass inner surface where possible; original press-molded panels will have two smooth sides, while aftermarket parts often have an unfinished side. "Look around the corners of the hood," suggests Kenny Yager, director of research and development for Mid America Motorworks of Effingham, Illinois. "Cracks will appear in flexible places, and you can tell if it's been broken before." Not all of the Corvette body is fiberglass, though; the steel frames that support the doors can rust if drain holes are obscured, and the steel floor pan will rust if moisture sits under the carpets."
