Tommy, I'm not a professional at this. The way that I finish the body might not be the best way. But, this is what I do.
You'll notice that I've ground off the gel coat and some of the fiberglass from the body where I will patch it. The idea is that I can add fiberglass and keep the new glass lower than the surrounding body. I use body filler to fill in any low areas and to blend in to the existing body. (note that most of the glass work will be done from the underside.)
Before doing body prep for final paint I'll put the body into a heated paint booth or go over every inch with a heat gun. If there is air trapped between fiberglass and the gel coat it will expand when heated and pop the gel coat. It's much better to catch and repair voids before final paint!
I make sure to wash the body and remove any mold release and wax. Then I scuff the body. Then I spray 4-5 coats of 2 part hi-build epoxy primer. Then I do sanding and final body work. The idea is that you don't want to sand through gel coat. If you do you will end up with tiny holes that will have to filled and sanded again.
On parts that that I make that have a raw fiberglass finish I use the hi build primer to get to get a finished surface.
I was thinking about the body all night. I wasn't happy with the rear deck angle. IMO it slopes to steeply to the rear. This is not a reflection of MR Bruce's body. It's a function of how I'm mounting it to my frame. (I've been very happy with the quality and symmetry of the body.)
This morning I removed the steel rear deck support that I had tacked in. I cut the body along the rear door line and down thru the rear wheel arch. I cut out about 2 inches of body length. Then bolted the rear of the body, through the upper license plate holder to the bottom of the frame. Then I angled the rear of the body to the front of the body until the angle looked right to me. I was amazed that the body line, at the cut, almost matched perfectly. I screwed the 2 parts together in prep for glassing together.
Because I'm using shorter than designed for tires there is to large of a gap between the top of the tires and the wheel arch. I temporarily screwed in some flares that I had to get an idea of what the looks will be with the gap filled. I'm trying to decide whether to lower entire rear of the body to eliminate the gap or make flares to fit. Opinions?
Pics with the changes.
Were in the middle of a snow storm so I've gone home for the day.