Greetings Eiolon,
we offer a character transfer option. You are eligible for it if you are in possession of a level 65 character on retail or another World of Warcraft private server with similar leveling rates to B2B. You can then issue a character transfer request upon reaching level 19 with one of your characters.
One character will then be leveled up to 65. This can be performed only once per account.
Aside from this there is unfortunatley no instant 60 feature you are missing.
You can find more information here: https://www.back2basics-wow.eu/community/index.php?page=Custom&pageID=16 couldn't find it in english tough - sorry about that.
Cheers
Nanoware