Shocker's are built to take anytyhing really mate. I'm currently using a HP 4500 Crossfire and it works fine. Not a problem. Some people find they get a steady air flow with Max-Flows.
As I said before, Shockers can take anything really.
But a suggestion is either get a CP reg or something or make sure vert. Max-flow is cleaned and lubed. If not it tends to be a bit crap. +/- silly ammounts.
Also a tip is on the vert. 'Flow there is a set screw towards the bottom of the reg, before adjusting the pressure loosen it up or you'll end up with brass shavings in your reg.
And because you are also a fellow Shocker owner (and for that reason I love you) here is a good tech. site for Shockers:
http://www.zdspb.com/
Have fun with your new toy man.
Russ