Preset regs on a mag
Shouldn't be a problem, just make sure you get one with an output pressure of around 800 psi to keep the flow up, and the mag valve will quite happily do the rest.
I run a Flatline because i'm a tart to be honest!
A team mate ran a preset centerflag job on his mag for abour 18 months. He had lvl10 ( which forces you to run higher input pressures due to the heavy springing), hyperframe and the air system kept up with it fine.
Laterz
Ian