Given, you already have obtained
insurance, I'm not sure what your question is. If you feel the upgrades you make substantially increase the value, you might want to have a
survey or by other means document that the boat is now worth more and increase the insured value accordingly.
Realize that regardless of insurance, the costs of restoration will probably fall far short of the increased value of the boat.
Also, I'd contact Boat U.S. and ensure that if you have a claim during the boat restoration process, that the unfinished nature of the boat does not in any way decrease the value.