Only one way to correctly fix rusted out panels and that's to cut out the bad and weld in new sheet metal.
I have repaired small holes (up to about 1/2 dollar size in hidden places using the following procedure.
Clean all loose rust away. Grind, wire brush, sand etc. to get it as clean as possible around the hole, for a few inches. Paint the area with a rust converter. (I use corroless from Eastwood company) Auto parts stores should have one. Once the rush converter has dried according to directions, I mix up a little epoxy metal putty (available at auto parts stores) and form it into two disks a little bigger than the hole. Then I press one onto each side of the hole simultaneously so that it sorta makes a plug. I try to work it smooth and work the edges down to a nice transition with the sheet metal. This stuff gets hard in 15 minutes so there's not much time.
After it dries for a couple of hours I sand it, paint it with rust converter and when that's dry I paint it with a finish coat on the inside, and rubberized undercaoting on the outside.
I only do this in areas where it does not show (inside the spare tire well, under the carpet, etc) and I've been fortunate that my Z only has about half a dozen rust spots.
Hope this helps.
Bob A.
> My 1976 280Z has rusted areas in the floor
> panels which penetrate the floor, including
> one area approx. 6 inches in diameter. What
> are the recommended ways to repair and/or
> replace? Where can parts be found?
> I know nothing about Z's, although I am
> learning fast.
> Any information is much appreciated.