Greetings from Solveig! Alas, all of my Japanese linguistics books
appear to be in storage at the moment. Also, as I will be forced to
relocate very soon, things are much more likely to go into storage
than to come out of storage for some time.
Regardless, you might check out the books by Roy Andrew Miller
or Susumu Kono. (Note. These names are from memory and may
not be accurate.)
While I do have my copy of Phonology of 8th Century Japanese
out on the shelf, that will not help answer your current question.
However, please remember that kami also means "hair" and "paper".
The various kanji used in titles appear to be consistently read as
"nokami". However, there are a few other headman titles which
appear to be rather older.
Your Humble Servant
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