The first steps were the easiest... Putting a pinch moulding around the sharp edges of the fibreglasss buckets, cutting the oval cutouts from the seat back, installing plywood strips for stapling purposes, and installing seat sliders. Mine were from EMPI and worked very well. The bottom seat upholstery is actually a separate piece, pulled over a plywood base, glued, stapled, and later bolted down to the bucket...
After seeing it done by Danny Gray on the motorcycle shows on TLC I used an electric "turkey" knife to trim the foam to shape.
I used a small sanding pad on my die grinder to rough up the fibreglass in preparation for glue.
The vinyl is stapled to the inner strips, then stretched around the foam and glued with spray glue on the backside. The wrinkles are a result of the reduced side bolstering, but I tried to make it consistent on both seats and I actually like the look.
The rear seat was pretty easy. Basically a 1/2" plywood base, cut to fit the roll bar, 2" foam on top trimmed to size, and the pleated vinyl stretched over the assembly and stapled.
Here are the finished seats. I wasn't comfortable with just the glue holding the vinyl on the backside. I fashioned plywood strips, then stapled them (believe it or not) to the fibreglass with my air stapler. The fibreglass actually clinched the staples, so there is no way to pull them out! These cleats do a great job of holding the vinyl against the glue.
The door panels are 1/8" MDF, cut to size, with vinyl glued in place, then screwed to the door with stainless screws and fancy washers. The speakers were screwed in place and wired through plastic conduits looped around the hinges.