I am turning my 75 Duster in to a Demon. I have a Demon parts car so it made it real easy. I would recomend trying to find a parts car as you need a lot of parts to do it right and it may cost less that way. But if you cant find one you will need.
Hood, fenders, grill, bumper and bumper mounts, front valence, grill suport.
The doors are different. The inside panel is plastic and the door latch and window crank are in a different spot. Also the glass is different. If you change out doors you will also need to change out the window track/wether striping or there will be a big gap in betwen the window and the roof line.
Some of the interior parts are different like the rear sail panels. The ones in a Demon are metal and the ones in your Duster are plastic. The rear 1/4 windows are also a little different. You can change this all over but again you wll need to change out the wether striping/window track.
Rear you will need a
Bumper, bumper mounts, rear tail panel, tail lights, tail light brackets.
You will also need front and rear wiering harneses for a Demon.
I am sure there is more but thats all I can think of for now.