I only ground off the gel coat in areas where the damage was. Most of my top was in pretty good shape. I had the cracks along the front of the visor. I ground those out as close to the gutter as possible. I didn't want to take the heads off the rivets. I ground back towards the center of the top far enough to get a good lap and tie in. I had a couple of other small spots where the gelcoat was cracked. I ground those off too. I course sanded the gutter, so the new resin would have some tooth. I also ground around the two light holes so they could be repaired. I used some glass mat on the holes. I used some fabric on the other spots. I would think leaving as much of the gel coat as possible would be best. That way you can keep the original shape of the top. You could use more then a couple of layers of fabric if you want to be extra anal. I was amazed at how much more strength it had after just the glass sheeting. I then used some kitty hair body filler to bring it up to the level of the gelcoat.. This is some tough stuff. You want to knock it down before it gets too hard. It is tough sanding. The kitty hair really stiffened it up
After it was all rough sanded I skimmed the areas with some Rage Gold. I finished blocking it out, primed it with some primer surfacer. I then painted it with with a single stage paint. I also used some zero rust on the gutters before priming it.
These tops were pretty stiff when new. I had 2 friends with new 40s back in the 70s. Their tops were like a solid piece of steel when we took them off. I think the 40 years of flexing and removing the tops get things worked loose. Of course many people modify these vehicle to flex a lot more then they ever did coming from the factory. The circular cracks I think were from hail or else the previous owner had an enemy with a ball peen hammer.
