So how about a dual proc G3 system with independant frontside busses for each proc....?

I may have mentioned one of my projects in other threads. I had two aluminium cases made up for a pair of Beige G3s I want to use as Xgrid agents. They are very simple metal boxes with a lid which slides or lifts straight off. They are only about 3 inches high, but go back further (about 20 inches) as I inteded to rack mount them.
The change in dimensions was acheived by moving the CDROM drive and floppy from above the logic board (where they are in the original stock case) to in front of the logic board. So all the components (logic, floppy, CD) would be on the same level, with the HD mounted above the floppy drive.
I have delayed installing anything in the new cases since I can't find my Dremel, but I thought I'd finally give up looking and make do with a drill and a hacksaw. While I was measuring out the mounts for the logic board, I noticed that I could dump the CDROMs and floppies, and fit both boards in just one of the cases (leaving the other free for something else later - sadly not big enough for my Xserve).

I will need to extend the ports on one board to the back of the case, but aside from that, its just a matter of finding room for the HDs (not essential, I could always net boot them) and some cooling. Both chips are only 266MHz at the moment. I'll swap them when I can get hold of some faster ones, but an overclock will have to suffice in the meantime. So some fans on the front of the case and some ducting may also be in order.

Anyone know of an ATX PSU which is 3 x 3 inches (or less) x any length up to 18 inches? Its also gonna need to be at least 300W....