1971 Duster 360 4 speed
First off, from the two photos you posted the car looks very nice. Any high rez. interior pixs.?
Are you a dealer, or if not, how long have you owned the car?
IMHO keep the car "AS IS" without hood scoops.
Rear deck - Go Wing type spoilers, and non-functional hood scoops really do nothing to enhance value or appearance of the car. It gives the car a little racy look, but when resale comes, unless the car was a real factory Twister equipped that way from the factory, and that's documented - proven, fender tag-build sheet, etc., it's just tacked on. Gives the car more of a hot rod appearance, and you could lose potential buyers. HEMI Mark has a lot of good insights on this.
You can sell those scoops for good $$$ to people on this site, restoring real factory Twisters.
UPDATE: the seller has put a lot of WORK , time and money into this vehicle, since January 2010, when it was listed for sale at $4,000 then lowered to $3,500 ...
Good luck with the Sale!