It appears the sunfire 280R has is sparc64 architecture, from distrowatch.com it appears the only live CD is
Gnustep. You'll want to download the sparc64 version (not i686, amd64, etc).
Debian supports sparc64 to install to the hard drive, but I'm not sure if
Debian Live can build sparc64 images yet (I believe their future plans are to be able to build a live cd for any of their supported architectures).