Does anybody know of a server-PSU-sized ATX PSU?

I'm working on a Powermac G5 project and I'd like to know if there are any regular PSU that will fit within the clearance of either at the top of the case (~3.5in) or at the bottom where the original one comes in (~2in?).

I wouldn't want to mess with an ATX to G5 PSU conversion. Or cut the top shelf.

Thanks!