Looking at Google images under kaigunto pulls up a lot of images just like the OPs.....I am not a koshirae expert, but given the amount of space he is trying to make up, the kaigunto tsuba set seems to make up the most space, and fit the theme of the koshirae. Maybe someone who has a kaigunto can chime in.
I thought the point of your issue is that you have 7.5 mm of space to take up between the tsuka and habaki....how are you to do that without a thicker set? Is this not a military koshirae similar to or actually is the kai gunto?
I am not seeing mitsumune, just a flattened area near the nakago. My referring to Late Koto is meaning mid to later 1500s. A trained polisher should be consulted to see if the hakobore can be dealt with properly.
Late Koto machi okuri possibly suriage sword with a hakobore the depth of most of the hamon; unlikely to be cost effective or possible to polish out, in my opinion.
The Naval swords had a pretty thick setup as well, with multiple seppa shaped to match the tsuba....someone expert in that kind of koshirae can help more than me; however, if i can help you, do not hesitate to ask.
I think you are speaking of the thickness, yes? That would be really thick I think; maybe the habaki or tsuka were not original to the koshirae. A bit tricky to resolve, might have to send it out to get it worked out, if your measurement is correct.
There are inexpensive tsuba to be had if you look around; the price you paid was not bad.You will want to take measurements of the width and thickness next to the habaki to find a tsuba that will fit. Enjoy your sword!
I do not think that the samurai who lived during the Edo period could have assumed that there was no need for battle ready blades, as their whole focus was on being ready for battle at a moment's notice. It is our retrospective that allows us to make such judgements; at the time, they probably wanted the best sword they could afford....how many were dismayed and disemboweled when the flashy hamon sword was broken in a duel by a superiorly made sword? It is a common theme in chanbarra films
Dear Ian, SAS stands for Steven Arthur Shimanek.....aka Steve the Bald.....Buckethead is a talented guitarist; me, i try, but not close
Steffiieee, there is a book on tsukamaki that explains numerous styles that would be good to have and may answer some questions; it is early here and i am not awake yet, but i think Buck is the author's last name.