Is an Ithaca double from 1914 with a damaged stock worth restocking and repairing?

That will depend on what is damaged and the condition of the remaining pieces. An Ithaca double is worth at least a few hundred dollars in operating condition but if it's a wall hanger, it's worth what you can get for it. If the stock is the only damage part, you can price a replacement at gunpartscorp.com or take it to a gunsmith for appraisal.