Many thanks for the comments, it's all a bit mysterious. Thank you Trystan for translation, thank you Ray for Tsuba input, I agree. Thankyou Bruce and Chris.
My overall feeling is that we have a here a Kai gunto that has been 'fancified', but by whom or when I don't know. I was hoping it would turn out to be a nice high end or presentation Gunto, as mentioned by Chris.
I feel the fittings may have been re-gilded, and at that point a fancy tsuba added, but again I can't be sure.
I did consider all these things before buying, based on photographs, but I thought it was worth the risk, and thought the investigation might be interesting, with help from you guys.
As I have some not-bad army gunto, but no Kai gunto, am tempted to replace the tsuba with a good quality 'standard' kai-gunto tsuba and seppa and keep.
Thanks for input, if any more ideas come up, will still be much appreciated.