Where is your fuel tank located? If it's still inside the cab, a true vapor lock situation would be nearly impossible, because there's a gravity flow from the tank to the pump. The old flathead Fords and some of the early Cadillac OHV V-8's had chronic vapor lock problems because of the distance the vacuum side of the pump had to lift the gas, over 13" in some cases. Gasoline under high vacuum conditions and high temperatures will vaporize in the fuel lines, and the pump doesn't like to move vapors, only liquid. If the pump is at or below the outlet of the tank, vapor lock is highly unlikely.
What can, and does happen is a vacuum leak that develops at the inlet check valve of the pump. Remove the inlet line and adapt a vacuum gauge to the pump. Run the engine at idle for a few seconds on the fuel left in the carbutetor float chamber, then shut it off. The gauge should show 10 inches of vacuum or more and hold the reading for several seconds after the engine stops. Not enough vacuum, or an immediate loss of vacuum is good reason to replace the pump.
A similar check should be done at the outlet. First, pump gasoline into a container with the engine idling. A good pump should produce at least a pint of volume in 30 seconds at idle speed. Pressure on a gauge should be 3 to 5 pounds with the pump deadheaded against the gauge, and should stay put for several seconds after shutdown.
I used to run the pump test in this sequence- - - -volume, then pressure, then vacuum. Failing either the pressure or vacuum test was cause to replace the pump. Low volume, but good vacuum made me check for tank pickup restrictions, and/or a kinked or clogged line from tank to pump. 13 years of driving a high-performance flathead Ford V-8 gave me lots of practice at fuel pump testing. Most of my fuel supply problems were solved by using a Carter fuel pump!
Jerry
