Advice needed on Mustang re-sale

Hello, I picked up a triple-white 1992 Mustang GT convertible at a good price. It's an automatic and everything works, including the power windows. It is in good shape and runs well. I intend to clean it up and re-sell it. The right side door apparently was sprung open at one time, damaging the door and fender edges. Repairs were made and the door and fender were repainted. Both the repairs and repainting were not well done and are noticeable. Here's my question: I can have the door and fender edges smoothed out and refinished and the fender and door repainted for $400. At that point, I will have $4,800 in the car. I'd like to make $1,000 on it. Will I be able to get $5,800 or more for it or should I not spend the $400 and then attempt to sell it for at least $5,400? I have already invested $400 in new leather for the front seats. The top is near perfect and the rest of the body is great. The car has only 76,000 miles on it. Your expert opinions will be greatly appreciated! Thank you.