[Coley]

At first glance....looks like a fair $5k truck.....might be a bit more and might be a bit less depending on the detail specifics that are currently unknown.
If the truck doesn't run....it is not worth (much) more than that, period....so that may actually play out in your favor while establishing value.
Negotiate respectfully with him and respectfully assert that the truck doesn't currently run so you have to work that into your budget.
Keep trying tho'......but hold your ground.
Remember the 'flake factor' in having something for sale is sky high when it actually comes down to people actually showing up...and presenting money, so that is heavily in your favor.

Keep us posted.
Coley