I would suggest going to an "antique gun dealer" and say this gun is not for sale but I'll pay you for an appraisal. Actually what you are saying is that he has no $interest in buying or brokering it but giving you a value based on expertise and receiving a fee for that and research. But any antique that has been restored etc can sometimes be the kiss of death. But, the value would be based on what similar restored guns are worth by comparable sales, supply and demand and condition
WBH
WBH