One thing you have to remember is that a positive displacment pump is not a sucker, it's designed to push fuel. Sure it has some suction due to the vacuum created in the fuel line, that's why most people run front mounted fuel cells on drag cars, and even then they are mounted with the bottom of the tank close to the fuel pump level.
On the round racers, if you're talking about sprint cars, their tanks are mounted high and most of them drive the pump off the back of the cam.
JMO
Zip.