Japanese Plums with High Chill Hours

I have Santa Rosa and Methley plum trees, however I have yet to enjoy the fruit of my labor, pun intended.

They've only been fruiting for two seasons, and it did seem like we had an unusually long heat spell in early spring followed by a very cold period in late spring, so it may just be bad luck.

Based on my understanding, a lot of the Japanese plums have been bred for growing in California, with very low chill hours.

Each year, mine have broken dormancy very early, and the fruit gets destroyed by a late frost.

Is anyone growing any tasty higher chill hours Japanese plums that can make it through late frosts better?

Emerald Beaut looks like it could be an amazing tasting plum at around 700 chill hours!

Looks like it blooms late, is harvested really late in the season, and hangs on the tree for a long time too!

Is anyone growing it?

The Toka (Bubblegum) plum is supposed to have low chill hours but has a late bloom time.

The skin is said to be slightly tart with sweet flesh that tastes like bubblegum when its fully ripe!

This tree is a cross between Japanese and American plums and is supposed to be extra cold hardy too!