70 Boss 302 Project value

[L16pilot]

I know of a 70 Boss 302 Mustang that isn't for sale today...but I'd like to be prepared if it does in the near future I've known this car since 1980 and it was parked as a running/driving car in 1987. I snapped a few pics in December 2008 and I am sure it hasn't gotten much worse since...not any better for sure. It was originally Grabber Blue and was last painted white in 1978. It retains it's original drive train....still has the FoMoCo tag on the Holley carb. Body has always been solid, but it needs a complete tear down and full restoration of everything. Original shaker, slat and spoiler car. No clue if the engine even turns over, but I'm thinking it's likely frozen due to the semi-open storage for the past 30+ years. Approx. 110k original miles and I know the engine was rebuilt in the 1985-ish time frame.

Not looking to steal it...just trying to understand fair value knowing this would be an extensive restoration effort. Any help / guidance would be appreciated.