Migrating a website is different from migrating phpBB - those are two different things.
It's obvious to not do this in the live environment before not having done this successfully in a test environment, and not without file and database backups either. Check if your 2.0.x installation is unmodified by comparing files and database tables with an installation package - modifications will complicate things. Similar usernames might need to be changed.
If the board's address changes (which includes using a new domain) then URIs to posts/topics/forums in post texts need to be migrated, too.
The worst thing about censorship is ███████████