The floor pans wasn't in too bad of shape taking into account the age of the car. But they did have a little bit of an issue that needed some attention. I welded the small holes on the rear passenger floor with a mig welder. When I started welding on the front pans the welder was blowing holes in the thinned, but still structurally strong, metal. It was time to go to plan B before I blew too big of a hole. I used a pressure washer to knock the old seam sealer out of the cracks between the wheel house and trunk floor alone with loose flakes of rust. I then sanded the floor pan with a flap wheel on the angle grinder until I found shinny metal. I used a sandblaster where the flap wheel did not reach. That was a big mess to clean up after. After a good cleaning with acetone I brushed on a coat of Rust Bullet. After that dried to the touch I placed a piece of fiberglass fabric soaked with Rust Bullet over the small holes and pushed the air out with a Bondo squeegee. The next morning second coat was applied. Later on that afternoon I started on the driver's side. Instead of sand blasting this side, I decided to do this by hand. I welded a 4"x5" patch under the brake pedal to cover the hole. I decided to sand the red primer off to see what was hiding beneath. Surface rust was everywhere. I used an air grinder with 80 grit disc to knock the primer off. Once again after cleaning things up good with acetone I coating the driver's side, rear seat platform. Before moving to the trunk area I welded the bumper mount to the trunk floor. The holes left over from the '74 and '73 quarter extensions got patched with small piece of sheet metal on the back side and the other side was filled with a puddle from the mig welder then grinded down.
While rinsing the luggage compartment with a pressure washer the bed liner that the previous owner sprayed peeled off. I decided to make another mess with the sandblaster in the trunk area and the backside of the quarter panels. After vacuuming and blowing compressed air the better part of the day I then sprayed 2 coats of Rust Bullet to the trunk floor and the inside of the quarter panel. Fresh seam sealer was applied 48 hours later. I brushed 2 coats of bed liner from the heater box to the tail lights and inside the quarter panels to add mass to metal surfaces to help in reducing reverberant sound. Aluminum faced insulation is also draped behind quarter trim and seat back. I will eventually coat the sheet metal and webbing inside the doors with bed liner. Next I will add a layer of Peal & Seal on the floor and wheel wells using aluminum tape on the seams.