I don't have hands on experience with Kakis, but there is no issue whatsoever between 60 and 90 chromosome persimmons as far as grafting compatibility goes.

This is a picture of 90 chromosome northern scions grafted on to 60 chromosome wild southern race root stock in VA.

Thanks. The N on S graft was to be the first I would try and your findings are very encouraging.

GB,

I had some interstem 90C D.V rejected Kaki grafts. I then cut out the interstem and regraft the same Kaki variety low on the original D.V rootstock and it took without any problem.

Tony