As far as I can think, it should slide right in.  If not, it may just take some smaller modifications.  Dual processors are nice, but you may find that putting that money towards a single G4 upgrade for your Sawtooth would be more economical.  You could just sell your G4 and buy a newer version too.  The GE G4 motherboard, cpu and power supply would be pretty expensive...more in fact that just buying the whole Mac!