[JLMounce]

This would depend somewhat on the fuel pump you end up using. It would need to be appropriately sized so that a decent volume of fuel it's providing is being consumed, instead of returned to the tank.

If you end up using a larger pump than you need, you can end up in a situation where you need as large, or even a larger return line. Otherwise you build pressure in the return line which causes pressures to creep at the regulator as well.

My experience with FiTech on my 462 leads me to want to be pretty cautionary about the return line. I tried using the factory return line in my original tank with an in-line pump and it never worked. When the engine was cold and needed much more fuel, it was fine, but as soon as temps came up and the engine leaned out, I would start back-building pressure through the return. This caused a rich/lean surge in the system as the additional pressure would increase flow through the injectors. The system would see this rich condition and pull back on duty cycle until I'd get a lean stumble and the system would fire the injectors. This was bad enough the car couldn't even be moved, let alone driven.

If you want these systems to perform reliably, you can't cut corners. 90% of the failures you read about on the FiTech or Holley forums and groups are because somebody tried to cut a corner either for ease of install or to save a buck. I'm going to be extremely blunt here about this. If you don't have the budget or the time/patience to install one of these systems correctly, you're better off not doing it at all.

The carb is much more forgiving than these aftermarket EFI systems.