Thanks for all the input on a gunsmith! I will contact NECG.
One commenter mentioned that the sling stud on the barrel would have to be welded...I don't follow that. I have seen many that were "screwed" to the rib. Maybe I am missing something on that.
Regarding all the comments on slinging a SxS...I guess I don't follow all of that either. A sling is very handy and, if done correctly, does not at all distract from the usefulness, appearance or aesthetics. To those concerns about it getting in the way...that's when you take it off (which I will often do via quick detach). Slings were universal on European doubles for many years - doesn't' seem to diminish the use or value of those old Merkels. You wouldn't dream of a fine rifle without a sling. I guess aesthetics are a very personal thing. I actually think they look better with a sling. You don't need a stool to shoot doves, but I always take one.
One last point...both of these guns will spend a lot of time in the turkey woods...among other places. Why would you shoot a turkey with anything else???
Cheers!