Where to install level kit?

SoCal Suspension is probably the best known aftermarket suspension shop I can think of in San Diego.

But realistically leveling kit installs are extremely simple, any legitimate shop should be able to do it. They are very much "do in your driveway" sorta installs. Not complicated at all, and any non-comatose mechanic with a with ~6-8 months experience on the job should be able to install it no problem. When I used to help teach an high school automotive class, we had sophomores (15-year-olds) installing them. The limiting factor will be finding a shop with a tire balancing machine capable of balancing 35s. Many tire balancing machines max out around 32-33s.