Actually, insurance companies have to look at comparable, not just KBB. In your case its a specialty car so that could mean a larger search for comparables.....you need to do your own research on comps to present them so that you can convince them to pay the 5K to fix it vs salvaging it.

Hope you have your Dinan receipts as the bolt on items can likely be claimed against the other company but it will be harder to do so on yours.