360 block limits

Fuel pump has zero to do with the delivery of the nitrous.

Fuel can be regulated by pressure, although, fine tuning using pressure is a PIA. Easier to use the pills to regulate the amount of fuel provided to the system. Is there a desired pressure for tuning, yes. Can a system be tuned with less or more fuel pressure, absolutely. It's a math equation to get the proper ratio of fuel and n2o into the engine.

If a system has a fuel jet equal or larger than the nitrous jet, it's typically a FAT tune. Almost always the fuel jet should be smaller than the nitrous jet.