In order for fiberglass to be a LOT lighter than sheet metal, it has to be thin and weak, not stuff that's good for street duty. (Vettes are heavy cars)
Of course, carbon fiber is an option that makes it thin, light and strong, but then it's big bucks, and you could just add more hp to the motor cheaper than using carbon fiber for weight savings. Aluminum body parts for the II would be pretty cool, though. Preferably, the entire skin of the car made of alum, like an original AC Cobra.