Mike
I am afraid it becomes even more complicated.
Both Kunitsuna blades I have also have the "Echizen ju" on the ura side of the nakago and the katana is a clear exemple of the Kambun style.
The mei matches rather well with the one on page 234 in Fujishiro's Shinto Hen. Fujishiro rates him chusaku and places him in the Kambun period. He also gives only one Kunitsuna from this school.
Does this mean there were 3 Shimosaka Kunitsuna?
Paul