Not a C-More, but we've run Burris FastFires on them. They were fine with the .375" rise spacer set. Have you already exhausted the range of your stock adjustment spacers?
If so, here's an option that might work with the 930 stock, but may require you to install the drop spacer set in your stock to get it dialed:
Again not a Cmore but did mount a bushnell trs-25 on my spx for deer season. Seems to work pretty well with slugs. Right height to cowittness with the irons.
Standard stock, not pistol grip.