1. I am no expert, but I am a student of Corvette history
2. I have heard before, and most recently just saw it again confirmed (on the corvetteforum) that only very early Corvettes (like 53's) had a gelcoat factory applied. So the big General himself didn't do it that way, if you take good guidance from that.
3. As for how to best approach in this matter if engaged in prepping my Corvette (65) for the very best result for a new paint job starting with a bare (sanded, media blasted? another debate!) body, I only know what was done to mine back in 1997 during a frame-off resto (Prior owner) - no gelcoat. I have not had to make that decision yet myself.