At this point, it does not look like you can download an iso version of PPC 7.1, but you do have options.
It looks like the best idea is to go to the SuSE distribution page, find a local mirror site and download the PPC 7.1 from there.
(You'll find the list of ftp sites at http://www.suse.com/us/support/download/suse_linux/index.html)
Next, follow Rolf Schmidt
I check munch site, include linuxiso.org, http://www.distrowatch.com/suse.htm http://www.softlandindia.com/Linux/LinuxDistributions.htm and more...
hthen where download this software suse linux