I would suspect a 2-dr door skin would be the same, sedan or hardtop, as the inner shell of the door would be the same length and height. I also believe that, upon close inspection, you can see where the sedan's upper frame is tack-welded to the inner structure at the top of the shell, at the belt molding, rearward of the lock button. There might be a similar situation on the front, where the vent window area is similarly tacked onto the door shell. The rear of the vent window assembly/window front run channel should unbolt from the shell, internally, hardtop or sedan. As the door glass would be different, might be necessary to swap out the window regulator, too.
As simple as it might sound at first, there can be quite a bit of work involved in such a conversion.
Depending upon how bad the existing sedan door is "mangled", I would think a good body tech should be able to re-form the metal with hammer/dolly work, plus drilling some "pull holes" to use a slide hammer to coax the bent sheet metal back to where it can be worked and straightened, so a minimum of filler is needed to make it look decent.
Fury series 2-dr sedans would have been the "base model" cars. Cars that were the least expensive to purchase and usually low-option vehicles. Think "municipal fleet", or similar. As such, they were used and discarded when their "life" was used up. Two door hardtops were much more prevalent, I suspect, especially in Fury III variations.
Salvage yards usually have a locator service between themselves. Places like LKQ or Copart might be a source, too. With any regional/national search, "freight charges" might apply.
Good luck,
CBODY67