Repotted. It took a lot more pruning than I'd expected. There were plenty of roots left, but I cleared out to almost right up under the trunk. I got rid of downward facing roots, crossing roots, and wrong-facing roots.
I repotted it yesterday out of some pretty dense soil. It actually has REALLY nice flare under the soil, but I kept the nebari you see to tie it in. The base is completely flat as well. (Lava, akadama, pumice, and 8822.)
Soil is a big issue, but once you've got that sorted, you need to look into how to secure the tree into the pot so that you don't have to keep repotting it. Here's one of the best resources I've seen on the topic: https://bonsaitonight.com/2016/12/27/secure-bonsai-pot/
I was given several bags of NAPA #8822 this year and I sifted one bag. I got less than half that seemed to be usable that didn't go thru my smallest sifting screen. Does anyone have pictures of rootballs that were growing in this stuff?