That ought to be a real scream at 200 MPH.
You would, of course, dig a tunnel under the Sierra Nevada mountain range. Starting from Sacramento end, you may be able to get away with only 60 miles underground. It also will be only twice as long as the Seikan Tunnel, which is currently the longest and the deepest railway tunnel in the world.
The cost of such undertaking will be trivial, since it's not your money. The Seikan Tunnel cost only US$3.6 billion in 1988 dollars. I'm sure the proposed map has more of such little details, and they can't increase the cost of this mammoth construction more than tenfold. Or a hundredfold. Who is counting among friends?
Perhaps a new way to find revenue???? A whole new version of a Disneyland ride.....