Pontiac GTO (1964-1969)

This classic muscle cars can be very valuable if restored. It's one that actually could be worth more than the cost of restoration. The current value to a collector could be restored state less estimated cost of the restoration value. If you look at the results of the auction of eBay (and others) that may be able to estimate by looking for a car similar to yours conditions, and restored.

Note that if you do your own work, is a huge project and can take up all weekends and evenings for years. Then it is painful when collectors come to look at it and pick it apart. Once arranged a Ford '49. It was far from quality show, but perfectly presentable and manageable with it's great old flathead V8. I ended up selling to a collector of pieces, for less than it could have achieved if he had separated myself.