Wow. Cool idea, if the board fits, then maybe it can be done. The ibook will need its original screen, keyboard, trackpad (unless you work out something USB) and battery. Tough but worth it if you pull it off. Good Luck.
PB G4 15" 1.2ghz - Pismo G3 400 mhz - iBook G3 500 "Jukebox"
"SawSmurf" G4 500 - Quicksilver G4 Dual 1ghz modding...