Hi Mark,
I'm with Junichi, it is really an interesting tsuba, unfortunately lacking most of its original hira-zogan. I'm still struggling with old inlay school classifications, but I guess the best tag for this tsuba should be Kaga Yoshiro, and Momoyama period is a good assumption as well.
Please see: http://www.giuseppepiva.com/index.php/e ... tsuba.html
Bye, Mauro