I'm trying to figure out which OS X version and build I need to completely reformat and then re-install the OS on my G4 Power PC (Quicksilver 2002)

So I've started my quest for the correct information and software required to completely erase and then re-install the OS on my G4 Power PC (Quicksilver 2002) roughly 2 days ago only to be stuck and very frustrated! So I could more than likely figure this out on own BUT the OS currently installed is so screwed up I cant even safe mode start it.. so I cant get the information I need from the "about this Mac" details if it were running. Is there another way to figure the correct OS X and build I'll need to reformat. I just want to return it to it's factory state and then give it to my kid. Anyone's help on this matter will be so very appreciated. Thanks