About the only way to “calculate” chamber pressure is to buy the Quickload software. And I am not too confident about its accuracy. Otherwise, the only alternative is to consult reloading manuals which publish lab-measured pressure information. Measuring pressures yourself would be prohibitively expensive for the equipment required.

The load you mentioned should be very safe in any modern revolver. Power Pistol is in the same category as Unique or Clays Universal. You should be able to find tons of reloading recipes for those propellants.