I just realized that the McMaster guages are all Grade-A accuracy... I'll have to wait for VIAIR to respond since I don't know what class their gauge is.
If it's Grade-B, I can get something like this:
http://valvesandinstruments.com/3-1-...05-02l-60.html
Edit: Just measured and looks like the VIAIR is a 2.5" gauge face, so this one would be more applicable:
http://valvesandinstruments.com/2-1-...05-02l-60.html