Reduce Hydraulic Steering Pump Pressure

[portculisz4]

I am in the process of a power steering conversion to hydraulic and have eventually acquired nearly all the required components to start the work. I planned to use the LF-30 pump (110 bar) but have managed to acquire a pump from a 3.0 ltr X Series BMW in excellent condition. The pump physically is identical externally to the LF-30 so mounting should be the same but I am concerned as it is spec'd at a higher pressure (127 bar). I understand there is a method by modifying the check valve to reduce the overall pressure that the pump delivers but cannot find details on how to do this, has anyone performed this procedure.