One way to contact old users would be to run a script on the archive and extract email addresses from users that provided them.
I think this would likely connect with a few of the old users.

While I'm here, would it be possible to fix the very limited character limit in /lit/ ? You did fix this before the migration, but since then it seems to have reverted to about 5000 characters.

Cheers, and keep up the good work!