The character set of EBCDIC is a superset of the character set of
ASCII. In fact CP1047, the variant used on z/OS, has the same
character set as Latin-1. Only the encoding is completely
different.

As a non-ASCII platform, z/OS is certainly challenging for people
used to modern conventions, and that is exactly why a familiar
and easy-to-use tool like Python is so valuable there. As for
viability, there are some obvious difficulties with Python's
handling of source encodings, but as long as you restrict
yourself to the ASCII _character set_ in your source code, the
vast majority of things seem to work fine with my patch.

There are more details in my mail to python-dev, which doesn't
seem to have appeared yet. I'm not a subscriber, so it's probably
pending moderation somewhere. (I hope "The list address accepts
e-mail from non-members" is still correct information.)