I have ../Base91/base91-0.6.0 containing
a tarball download from
http://downloads.sourceforge.net/base91/base91-0.6.0.tar.gz
and the a few commits of my own; you can find it at
chiark:~ianmdlvl/public-git/base91.git
This will become a git-subtree merge, but those are annoying to rebase.