In the editor, if I look at the available resolutions it shows that 2880x1800 is listed, however the current resolution reports 1440x900.
For the build, I was able to get it to recognize the full spectrum of resolutions by setting the Mac Fullscreen Mode to Capture Display.
However, as you mentioned I have to run it in full screen mode to get the desired effect.
While not ideal, at least I have a way to preview the game at correct scale.
Thanks for your help!