I'm not 100% sure but my mind certainly leans to a no on this one. Besides, performance sucks in PCI CPU upgrades. Yes you can buy up to G4 700-800MHz upgrades for PCI but it will run about the speed of a G3 300. They are cheaper for a reason.

Here are 3 brand new options for you: http://eshop.macsales.com/MyOWC/Upgrades...s=Show+Upgrades
2 of them are below $150 and will give you MUCH better performance than a PCI CPU even if it did run.