I know nothing about code or the logistics of running an operation like these journals...but maybe there's an adaptation of the process that moved our journals from LJ? If you cross-post to another journal you lose the comment thread. But when we moved from LJ everything transferred except our journal style. Maybe that processes could be modified to work within Dreamwidth, to a new journal, that had a template that automatically ordered the journal entries by date oldest to newest.

Also, we can manually change the date in an entry, and the entries shuffle that way.
Maybe there could be an adaptation to that process?