well you need the best plastic epoxy on the market. i use some 2 tube black shit they sell at any parts rated for 3500 psi. you need to mock up the panels to your doors and behind the door and rear fender well on both driver and passenger side.
don't be afraid to chop the panels down the middle. also your going to need 1981 to 85 fleetwood 2dr rocker trims coupe devilles don't normally have them.