Sounds more like you need either a new gas tank, pick-up, fuel line, or maybe even all 3. If you needed to use compressed air to get gas to your carb., an electric pump will not do it for you. By using the compressed air, you pressurized your gas tank, forcing the gas out the easiest exit. How much psi did you use to get gas to flow? Yes you need to mount your fuel pump below the tank, BUT from your tank to the pump is gravity feed. You will starve your electric pump if you do not have a full flow of fuel to the pump.

Do what you want. Guys on here are just answering YOUR question and pointing out problems that you could possibly run into. Simply because they have seen or had these problems sometime in life.

Have fun!