Enter the super hero - Resin Fiberglass!!

With fiberglass, you can restore the floor pan - waterproof it, strengthen it, what ever.

I have a 78 242 that was rotting in the trunk, under the rear seat just above the frame, and the left and right rear floor pans were ready to drop out.

I picked up a gallon of resin (The boat type) and some fiberglass matting, at a fiberglass repair/manufacturing shop - their prices were much better than auto parts stores.

Wear latex or plastic or rubber gloves, the resin is nuts to get off your skin and the acetone is crazy on the skin.

Work in a well ventilated area - the fumes will trip you out.

Be sure to wear safety glasses and don't let any resin or catalyst drip near your eyes.

All these warnings - I still am thrilled with the way that the fiberglass repairs converted a drafty, exhaust ridden, dusty car into a clean tight quieter, warmer ride.

I restored: 78 242 - battery shelf, floorpans, interior of trink seams, rebuilt spare tire wells, outside rocker panels (patched holes), patched holes at rear of trunk,

86 245 - rebuilt busted turn signal lens, rebuilt headlight adjusting bracket on rear of euro plastic headlights.

Cost $50 Cdn. - savings $$ hundreds.

Good luck.
Grind surfaces to clean metal - large patches such as the entire floorpan can be attached by building a heavier lip and screwing into the side tubes.