Also, Notice where the white gas line goes into the regulator in your pic, that is the hi-pressur input to the regulator and needs to be either directly screwed into CO2 tank, or get the proper hose. Because regular gas line that we use Post-Regulator will not handle the 800PSI that this hose needs to handle.
As for the hi-side tank pressure gauge, I have 2 or 3 in my basement, but they read to 4000 PSI. I might have a 2000 PSI Gauge, I'll check. Princess Auto also have them I believe.