I have not read all of my FSM and have not noticed if they have a specific way to measure the Crankcase pressure with a Gauge or Manometer.
However, If you are having to much crankcase pressure and you are not going to fix the cause the next best thind to do would be to provide more ventilation.
Meaning create another additional vent hose setup or find a way to enlarge the present one.

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84 300D, 82 Volvo 244Gl Diesel