Same thing here with my 68 Ford Fairlane except mine does it while idling in a drive thru after starting it after a hot soak
Tow it home, starts next day. Glad I got AAA. This has happened twice in 20 years so it's not like Everytime I drive it. Just tends to happen unexpectedly.
One thing I found was the tubing going from the pump to carb was touching the water pump. Which might be acting as a heat sink.
Thinking of going to an electric pump.