500psi straight on will burst a ball like noone's business, so it will be perfectly fine. As a matter of fact, a paintball with optimum efficiency should reach 300fps off of a little less than 150psi hitting it. We found that out on a NecroRam project for an Intimidator, but the physics and math are mostly still the same for other markers.
With a proper spring kit, polished/lightened internals, and a good flowing valve (since you're going pump that's in the bag), I would hazard a guess you will be fine off 400psi. My Sniper is less since its a Cocker, but you can make a Spyder run just as low with enough fiddling and determination.