[JLMounce]

That may be due to different type of regulators being used. If you're regulating something without a return line, you're dialing down fuel delivery to the carburetor. With a return system common with an electric fuel pump, you need a bypass regulator. That works by sending the amount of volume necessary to create a given pressure while returning any remaining fuel back to it's source.

OEM's haven't had regulators in the engine bay for quite a while. With modern PWM pumps, most are deadhead systems that sent fuel volume based on input to a fuel rail pressure sensor. Those OEMs that do still use return style systems often have the regulator near the tank. I would say it doesn't matter as a result. If you feel more confident with it closer to your carb, run it in that configuration.