NEF does not make a Full choke with rifle sights. The best he could do is to buy one of the full choke models and have a gunsmith fit it with sights. There are a couple different length options in full choke. There is the standard 28"in full and the 24"turkey in full. NEF does still have some of the old Tracker I style barrels in 24" cylinder bore with rifle sights. That would be my recommendation. Cost from the factory $54+$15 fitting+$10S/H. Then, of course, there are the rifled slug barrels. But you did say he wanted Smooth Bore. There is one more, the 22" youth 12ga in Mod. Choke, but he would have to have sights installed on that one too. Hope this helps.
Just curious, why Full Choke?