Sorry for my late reaction.......
In my personal opinion it is a akasaka-tsuba.
Personal opinion, because this tsuba was not sent to a shinsa until know.
Some friends of mine agree with my opion that this could be made by the third or maybe the fourth master.
In the first book of Sasano (early Japanese sword guards, sukashi tsuba),on page 210 you will find an akasaka-tsuba which looks very similar to mine.
In the book it is a signed work from the fourth hereditary master tadatoki.
See picture 1.
Dimensions of mine: Height 86,24mm, width 83,14mm, rim thickness 6,33mm, rim seppa-dai thickness 5,70
Close distance picture from the rim show a fine laminated iron.
See picture 2.
Hawley