I have been dealing with NECG since Dietrich Apel days and have had a number of shotguns and drillings and even Mausers and Mannlichers run through their premises. I haven't visited them in their new location, however.
Dietrich rescued a nice little Greifelt S/S 16 gauge which I had found in a pawnshop by restoring it to its former glory. He also supplied the replacement screws for a Sauer und Sohn 12 gauge on a Kerner/Anson action. The previous owner had disassembled it and then lost all the original screws.
I have been thinking of having a period scope, such as a Zeiss Zielmar, mounted on the Krieghoff, assuming 22mm claw mount rings can be located somewhere, which would obviate the iron sight problem. I can't really see iron sights any more, anyway.