My husband's estate includes a 1970 Buick GSX Stage I. The yellow paint is good, the interior is excellent. We took it on a road trip with our classic car club 1 1/2 years ago and it ran and drove great. How do I value it based on the Excellent, Good, Fair scale? PS: all numbers match.
Hopefully I can help, and I am sorry for your loss. I am the associate editor of the Hagerty Price Guide and get this question frequently.
Survivor cars do not follow the usual condition based formula of the typical price guide as much of the value lies in the preservation of the car. Paint, metal, upholstery and more are only original once and when any of those aspects are restored a lot of that additional appeal and value is lost. A preserved car with documentation (build sheet, original bill of sale, window sticker, etc.) may be in a condition consistent with a "good" or maybe in rare cases "excellent" condition rating per our guidelines, but in the right circumstances have sold for "concours" level prices in the past.
All that said, to establish a solid value, especially for settling an estate, it would be appropriate to seek an appraisal to help further the vehicle's document trail. It is important to keep in mind that if you go down that road, it is important to seek out an appraisal by an experienced individual who is accredited by a well established, and widely respected group like the American Society of Appraisers (https://www.appraisers.org/) or the International Society of Appraisers (https://www.isa-appraisers.org/) just to name a couple.