The finish panel is a piece of aluminum why not reshape it to fit the rear quarter panel. A couple pieces of wood and a rubber mallet and I would have that fitting perfect in less than an hour. I reshape the headlight bezels to fit the fenders on 70/71 Challengers all the time.

70 Charger R/T SE 472 Hemi 70 Charger R/T convertible 70 Charger R/T V Code Sixpack 69 Charger R/T SE Sunroofcar 68 Charger 383 68 Charger 318 71 Charger R/T 70 Challenger convertible 71 Challenger convertible 71 Cuda 340 09 Challenger R/T Classic