Why involve the mixer at all? I would plug your Heil PR40 directly into the Zoom H4N. That way, there will be far fewer controls to set and the sound quality will be better by not having to be passed through a mixer of that particular make.
Don't forget also that you can use the H4N as a USB audio interface for your computer and, rather than record the sound on the H4N and transfer it to a computer, actually record the sound directly on the computer using some digital audio workstation (DAW) software such as Audacity or Reaper. One reason I suggest this approach is that it is much easier to view the waveforms live on the computer monitor than using the information on the small H4N screen. You can easily see whether you are too low or too high in level, and make the adjustments to the H4N gain control before you start recording the main take.