I replaced the water pump.
I replaced the head.
I replaced the upper radiator hose.
Twice.
The second time with an $60 silicon radiator hose from Moss Motors.
I replaced one of the heater hoses.
Nothing is leaking.
I replaced the thermostat.
I replaced the heat sensor on top of the thermostat.
Both fans are running.
I changed the wiring so that both fans are running at the same time all the time, bypassing the relay that turns one of the fans on when the thermostat hits a certain temperature.
Just now I drained the radiator again. Changed the antifreeze with the Prestone 50/50 mixture. Added one half bottle of Water Wetter.
Drove it around the neighborhood for about 20 minutes. It overheated again.
What's left?