4th gen greyscale mod and help!

Okay so I'm semi-new here (of course if you discount my upsetting form on bypassing the fw screen which nobody helped out upon.) but I just wanted to ask a couple of things. So I have an old greyscale ipod classic 4th gen which I already replaced with a 20gb hard drive (NOT SSD YET). I just wanted to ask a couple things upon specs, limits, and firmware. First I have Rockbox firmware so I am able to play flac but then I also wanna play gb roms so I need some help finding the correct files for ipodlinux on my ipod. I know I can boot into ipodlinux via holding down play while booting up but the problem now is finding the correct firmware and files to boot into that. Then I would like to also know the limitations to how much storage I can upgrade my device to. Thanks and regards,
Thomas Hancock

via iLounge Forums http://ift.tt/2g7POaf