There are some minor advantages involving the lower engine, such as oil splash cooled pistons and I think even a harder and more expensive piston. The ECM is differnet of course. Its possible that the turbocharger wastegate is set to a higher pressure. Which only means if that is true that you could bump up the wastegate pressure to match or even exceed the HO flavor.
My guess would be that a fueling box would soup things up pretty good but I honestly don't know of any work that has been done to show what opportunities there are. The CA SO is different from the other "SO" engines to deal with the NOx output and so they've de-tuned things a bit to meet the CARB regs. A fueling box basically intercepts fueling instructions and delivers different ones, so any fueling box is probably not CARB approved. For example, fueling box mfgs say things like "for use in non highway racing applications only. not legal for street use".
But that aside, you might want to research the difference (if any) between the CARB regs for engine manufacturers, and the emissions testing requriements that allow you to keep the truck registered there. There might be a difference. I would imagine the laws are pretty strict, but who knows, Sac town might be differnet from So Cal.
You have to test vehicles for emissions every year, right? I'd go to those places and try to find out what the limits are and what they test for.
If you have an automatic transmission, though, it won't be able to take the additional HP, so you'd have to invest in some serious transmission work.
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