Not a stupid thread at all. Actually, you could buy CPU slot adapters
for 7300-9600 era (Old World PCI) Power Macs which featured a ZIF
socket for a CPU from a beige or blue & white G3, and adapted that
more modern CPU connector to the slot style connector of the 7300. It
worked well and even had jumpers for setting bus speed, CPU multiplier
and so on.

Back in the PegI prototype days, there were some pics which looked to
me an awful lot like a ZIF socket CPU (single or dual G4) on such an
adapter plugged into the Pegasos I.

There's no valid technical reason why the more modern 'MegArray'
connector used on Macs from the Sawtooth (first gen AGP Powermac) up
till the advent of the G5's couldn't be put on a card. The heatsink
would be kind of scary hanging off to the side, or you 'd need a
watercooler. In any event, a tall case would be needed but who cares?
Giga Designs makes a 1.8GHz dual proc PPC accel which fits this
connector. I think they may have it up to 2.0GHz by now. You say you
don't need more CPU (than a single 1.0GHz G4) but if you had two
2.0GHz G4s you might change your mind Their USA built and 3 year
warranted 1.8GHz dual proc G4 with 7447A's is only $495.

It could be like the Amiga days when CPU cards had their own RAM and
SCSI, well nowadays you'd put a SATA chip on there. Hey, if you're
gonna dream..