I have created a modification of the Captain Sim EPR gauge so as to give accurate readouts.  The FSX EPR variable simply does not work properly and I don't even know if that is what Captain Sim uses.  Anyhow, my modified gauge expresses EPR as a function of corrected N1.

Does Captain Sim have any position on distributing its XML files in modified form? I am not going to do that without its permission.  However, I could simply post instructions on how to modify the necessary files.  Does Captain Sim have any problem with my doing that on this forum?

To properly set power you still need a TAT gauge and power setting tables.  I am using a TAT gauge from another product -- it's not particularly difficult to find a gauge and add it to the panel.  The power setting charts are available on the web as part of the manual for another product. I don't think this is the place to give the details for that.