And Robert, it seems that Mishina Sensei did the second polish. And you are absolutly right, Naotane made a true copy incl. the 3 mekugi ana, the tang, etc. And yoshitane made a true copy of the horimono left over some hundred years ( evt. more skills on that )and Mishina sensei polished it to a true copy.
Excuse me for that twilight pics..
Do not find the original Nobukuni, may be it sleeps well without any internet in Japan. So there are only two people to answer the question !!
Best