I don’t eat sushi in SF anymore. I had gone to Sushi Yoshizumi in San Mateo quite a bit early on but it got very hard to book (it’s quite good, best in NorCal) and out of the price quadrant I’d want from a regular and impromptu sushi meal. But if anyone could make it good in the Bay Area, it would be Akira-san at Sushi Yoshizumi (they do a $250 menu with advanced notice; I wonder if saba bozushi could be requested). Tbh, I visit LA, Honolulu, and NY enough that I tend to just eat sushi while traveling (and Tokyo next year).
Kiraku in Berkeley does good shime-saba sashimi, but that’s different than saba bozushi of course. They do torch it slightly to render some of the oils (yes, it’s not warmed by the radiating heat of bincho, but Kiraku is a solid izakaya, not a high-end sushi joint like Noz in NYC). Not sushi, but you can have a solid meal with shime-saba sashimi, suzuki carpaccio, maybe corn tempura, clam & cilantro ramen, and end with a hojicha blancmange.
Edit: I saw pics on Ye*p - Yoshizumi does make saba bozushi.