article in 'tech tips' section about insuring old trucks.
http://www.stovebolt.com/techtips/insurance.html At the bottom of the article is a link to a list of insurance companies that specialize in older vehcile insurance.
You might find it useful.
The key is to shop around and agree to a value in writing up front, and keep up on the agreed value, again in writing, as you fix the truck up or if it becomes more collectible.
-W