Joe that is such a beautiful flintlock sxs!  It is one of my dreams to have a flintlock sxs that I use on occasion.  Have you ever shot this one?  
I have a few single shot contemporary flintlock fowlers that I enjoy as well as a few original percussion sxs shotguns that I do use now and then.  I did recently acquire this 20 gauge sxs that I believe was converted from flintlock:  
https://parkerguns.org/forums/showthread.php?t=34412
I do think this would be my chance to finally have a flintlock sxs and I will likely have this reconverted.  Do you happen to know anyone who you would recommend to do that re-conversion to flintlock?
Your flintlock sxs is a work of art!  Thanks for sharing,
Jay