vapor lock is a product of heat (and you Virginia boys dont know heat come to Texas and Hell's Half Acre to see heat). and usually the only hot spot on a old chevy pickup is where the fuel line passes real close to the thermostat housing (and sometimes when it gets close to a radiator hose top or bottom), but with a good operating fuel pump you should have enough pressure to raise the boiling point of the fuel to keep it a liquid and avoid that problem. It well could be that the fuel pump's spring has gotten tired.
to really test that theory try wrapping some asbesto (try finding some asbestos) around the fuel line at those hot places. If it runs vapor lock free, then leave it for conversation's sake or put on a new fuel pump.
