I was wrong about being wrong
Okay, so when I said I was wrong that the two Phillips screws going in from under the dashboard hold down the cowl... I was wrong. They do. It's clearly shown in m_thompson's writeup.
Nonetheless, there appear to be three different valid ways of approaching gauge removal. I was NOT going to take my air-conditioned console apart to expose some of these screws, so I wound up using the "pull the gauges out from under the dash" method.