Hard to say without pics, but 6 cylinder cars don't have a very strong position in the market right now. Especially with the two speed auto, and especially after being parked for an extended time. I just bought a nicely equipped 400 4 speed convertible for not much more than the price listed above. I'd say in the $6K range if it's a 1 bbl car.
But then again, some people spend fairly big money on eBay on cars that I wouldn't give a second look to. There is a batch of cars for sale on eBay now that are fresh out of storage and were mostly worn out when they were put in, and they are getting good money for poorly stored poor condition cars.
If it was local, I'd trade in my Neon for it.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching