Actually, the best place for the shutoff is before the pump... Should you have a runaway pump (ecu failure) and it runs at full pressure, instant shutoff at the valve could burst a line (has happened!). Much safer to kill the supply than the pressure
The location of the fuel shut off valve is only as good as your ability to reach it when needed. Once the jet is buttoned up and on the runway, or in the air, it is only along for the ride (unless you have a servo to close it).
If it is a Festo type ball valve, it should always be on the pressure side. If it has barbed fittings (and is safety wired, it can go on either side of the pump.