It is a standard Max Flo, but with some weird home-made manifold attached. Not sure there's an easy way to tell if it's a 3000 or 4500psi, but I'd guess at a 3000.
Best thing to do is get a new CO2 manifold from SP. You'll need to remove that bit of pipe from the reg and replace it with a nipple (I think it's a standard quick disconnect nipple but not sure) and stick the reg in the manifold.
Or you could get an Eclipse VRM, mount the reg in that and use it as a vertical reg (as long as you don't mind all the bits of hosing everywhere that entails.)