If they wanted to have a chance for this to work, and to have some reasonable number of passengers, they should have built it along the coast along the Coast Sub route connecting LA, Simi Valley, Oxnard, Ventura, Santa Barbara, San Luis Obispo, up to Monterrey and into San Jose. There is splits to SF and Sacramento. There are already tracks there that used to be the main passenger route when trains were king. Today there is little freight or passenger traffic north of Santa Barbara. There are fewer and shorter tunnels so the work is probably orders of magnitude easier.
Additionally CA should be upgrading the Hwy 5 corridor in the SJ valley. It's two lanes each way but with the amount of commercial traffic it should be 4.
Finally, spending money on expanding the reservoir system should be the top priority. Often times we get a decent amount of rain but it just runs off into the ocean. Are main reserve is the snow pack in the Sierras but if global warming is true, there is going to be less and less each year.