While my query is not really appropriate for this forum, Double Rifles is as close as I'll get. I have the fixin's for a percussion cap lock Over/Under howdah pistol partly assembled. It definitely needs a new grip/stock, plus relatively routine restoration. I seek an American gunsmith/restorer for it.

Following are photographs of a similar howdah, with an integral loading rod (mine does not) and a much smaller bore.

I would give Jack Huntington a call you won't be disappointed
775-355-6898
http://www.jrhadvancedgunsmithing.com/