September 13th, 2014 11:38 PM
First off welcome to the club.
You have certainly chosen a complicated build, putting different pieces together from different machines. Anyway, I am not sure how much help I can be on this project, since I have actually never seem an iMac G4, but I have had experience converting an iMac G5.
One question about your build is the iMac G5 20"...