I also posed the question to Derrin at brewershardware, he thinks my pump will work because it is direct drive and can generate the needed psi. The mag-drive pump might not generate enough pressure since its designed to slip when it gets more pressure on the outlet side (from closing a valve to reduce flow for example).
Edited to add: I looked at the max psi on a March 809 and it seems to be limited to under 7psi, so I guess a mag-drive pump is out for driving most any spray ball. I did see a smaller plastic rotating spray nozzle in McMaster Carr but it is more expensive than the one I have($50 vs $29).