No Corvette (except 53's) has EVER used gelcoat on any body panel; gelcoat is only used to create the smooth outer surface on "hand-laid" or "chopper-gun" aftermarket panels and things like boat hulls, hot tubs, and swimming pools, to hide the texture of the underlying glass mat or cloth. Corvette body panels are press-molded in matched-metal molds under heat and high pressure, and are resin and glass all the way through; the finished surface is the same as the surface of the mold.
Each painter has his own favorite products for priming and sealing stripped Corvette body panels; many in this area prefer PPG epoxy primer, followed by PPG sealers and topcoat materials.