The 280ZX 2+2 is about 4 inches longer in wheelbase than the 280ZX coupe. This length is mostly in the rear clip of the car.
In this photo you can see where cuts were made along the flattest part of the quarter panel.
In this photo you see the same cut extended across the rear deck area. Obviously this would not apply to a coupe.
This photo shows how the gaps are spanned with tileboard and locked down with screws.
In the next two photo, the rear clip is removed, turned upside down, and a wet layup of fiberglass is applied to the gap area. The inside surface of the rear clip should be sanded for best bonding, and the tileboard should be waxed or have clear packing tape applied as a release film to enable you to remove the tileboard cleanly.
This shows the underside of the clip with the fiberglass fully saturated with resin, and rolled out with a fiberglass roller to remove any bubbles.
Here you can see the rear clip back on the car, with the tileboard removed and the raw, cured fiberglass visible.
Use a high-building primer/surfacer to make sure you have all the pinholes sealed (any hand-laid fiberglass has some natural porosity), before you begin your final block sanding and paint prep.