Prices are from NADA.com's classic car section. I would look up Old Cars Price Guide and see how it compares. Looks like a 40-50K car. That was the last of the big dogs and less desirable Shelby, but very rare and still a lot of fun.
Low Retail: $46,600
Average Retail: $70,700
High Retail: $117,200
There was a yellow one in a storage place for 15 years near my folks house. It used to be a nice old beast, until rats & critters tore it up. Guy still wanted 100K for it last I checked...which was a joke.