why the jump to linux? os x is a great operating system and is based on unix. but, if you really want to i would check out the debian-installer for PowerPC and/or Gentoo as those seem to be the two best for macs.
Use XPostFacto or whatever it's called to install Panther on it instead. It will run acceptably on it. But I'd recomend Debian. Installing Linux on Old World-Macs can be a pain, and Gentoo is a pain to install in itself, so it's even worse.
You more have to worry about video for X in the 8500/9500s.
I ended up getting a 16MB PCI Rage from a B&W G3 on eBay to be able to run X on an 8500. It has a G4-450 in it, and 384MB Ram. It runs very well.
I have an 8500 and an 8100 and ive sucessfully loaded osX and linux on both. You have to load up an os9.0 partition and run xpostfacto selecitng the cd and clicking install or going up to the menu and loading the startup items.
Also you might have to manually reset the firmware
you access this area by restarting your mac and holding these keys APPLE, OPTION, O, F this will take you into an open firmware programing window
At this point you need to type
set-defaults
then hit enter
Then on the next line type
reset-all
then hit enter.
this will clear your firmware and load you into whatever os your trying to install if your holding C on the keyboard and have an install disc inserted in the drive.
Sometimes you need to strip the macs down to the bare essientals to get them to run these systems then one by one install the extras.
I hope this helps.