Use a tee piece into the sender unit hole but make sure you use a steel tee and fittings as the brass ones have a habit of cracking under heat and vibration .
I fitted a high compression 2T with fuel injection and bolted a 1GGTE supercharger on the side , Ran 12psi and had no ignition control and it used to detonate between 3000 - 4000 rpm but just drove through it and never did any damage so with good fuel and ignition control as not to get any detonation I think 15psi would be OK !!!