This^^^^^^^I've had carbureted bikes with fuel pumps in the past, they always shut themselves off( internally) at a fixed pressure . Anytime the engine was running they were powered. We're making this way too complicated here.
no return piping or anything. Make up a pressure gauge setup and power the pump up and see what it does. It's not that sophisticated I'm sure.
I used one on a bike with FCRs on a manual switch, no overheating of the pump or over pressurized carbs,
The pump stops pumping at a fixed pressure, low enough for the float needle to handle it.
All low pressure fuel pumps work this way. I can only assume there is a relay there to stop the pump in case the fuel line ruptures or something like that. It's not necessary.
Just find a switchable power lead on the bike and wire the fuel pump directly in. Or ditch it if gravity feed works ok.