You shouldn’t really have to setup anything for Crysis 1 normally. Under normal circumstances vorpX adjusts the FOV automatically for this game. Maybe that failed for some reason with your setup.
If you haven’t done so already, first and foremost please check the ‘Essential Hints Guide’ in the vorpX help. Among other things it explains how to deal with FOV if vorpX can’t do it automatically. Generelly checking the help will save you a lot of trial and error.
BTW: if a game feels uncomfortable in FullVR mode, ‘Immersive Screen Mode’ is always worth a shot. Another option would be switching to Z3D mode, which is a lot faster and thus helps with discomfort due to a potentially low framerate.