Thanks Thomas and John. My way to go around it was to compare it to similar sized swords in koshirae but im not sure how accurate that would have been. The nakago, 6", is only large enough to be held in one hand allthough the blade is heavy. It was made by the Dotanuki smiths, Dotanuki, Higo province around 1560, ancestry goes back to Enju Kunimura.The Dotanuki smiths made many swords in a time of war as you probably know. Picture is the only one I could in a rush before work, next to katana and wak in koshirae. That's not my carpet by the way, just a rug
Edit, should have pointed out nakago measures 6" after the habaki!, sorry, so nakago is rougly 7" approx.
I have read that shirasaya tsuka are shorter than koshirae tsuka. If I know roughly how much shorter they are, maybe that then would give me an idea of koshirae tsuka length?
Alex