Try four winds nursery. They have cultivars on Flying Dragon understock.

Four Winds doesn't seem to have them this year. Sperling Nursery in Calabasas has them, I bought one last week.

Went to Green Arrow Nursery in North Hills today, they also had them. They have a few locations. Green Arrow / Green Thumb.

On the southern edge of Riverside, call Atkins or Clausen nursery. I saw Kishu at Clausen last week. Dan