Fueling issue

Check the rubber jumper at the tank. If you have used gearclamps there, then you need two per side/total four, as the gearheads will squish the fuel line together and create a channel for air to get sucked in.
I'm assuming that you have proved that the tank is vented.
Finally, if you have Solid lifters, check that your Hot-lash is adequate.
In my experience, a hood scoop connected to nothing is worth nothing. Except when you shut the engine off, then hot air has a place to exit.
The next time this happens:
Immediately shut off the engine, and coast to a stop. Then Check your WET fuel level in the carb.
If this is not possible, carry a small funnel and a small container of gas, then when it happens, pour about 50cc of gas into the float bowl thru the bowl venting system. Remove the gascap, Then start her up and drive away.
If this works, but you only get a few hundred yards, then you have proved, the problem is
insufficient gas in the carb.
Now you gotta figure out the why of it.
re-install the gas-cap.
But if the car, continues to run with the gascap off, well, go attack the vent system and or that jumper I was talking about. While yur at it, do the same down by the pump....