I've never heard of the k3 CPU, but it looks like its not i686. Download and install the 2006.0 x86 stage and update world on it, or install from 2006.1 stage 1. I recommend the former, having never done a stage 1, and you will end up with the SAME thing either way.
I suspect that you used a i686 stage tarball, which will _not_ work on a k6-2. You need to either use the 2006.0 i586 tarball, or a x86 stage1 tarball from 2006.1.