Voltage/ Controller Combo to run a 5403 on the ragged edge?

[mainsource]

I want to apply a 5403 [running through appropriate short ratio gearing] to a situation where the weight of the motor/ controller combo is not an issue... Can I get the max performance from this motor [i will vent the side covers] using a Kelly controller? Are the Kelleys reliable? Any other controller recommendations out there?

Thanks a bunch Guys!