Hammerers are better than Longbeards.
The only reason to field Longbeards over Hammerers would be to use up the core percentage requirements.
I also wouldn't bother with the anvil of doom - you haven't got any miners, etc, to really take advantage of it. Although it will be good magic defence, you're probably going to be better off taking something else... maybe a combat Lord to go in with the Hammerers to make them immune to Fear and Terror?
The only reason to field Longbeards over Hammerers would be to use up the core percentage requirements.
I also wouldn't bother with the anvil of doom - you haven't got any miners, etc, to really take advantage of it. Although it will be good magic defence, you're probably going to be better off taking something else... maybe a combat Lord to go in with the Hammerers to make them immune to Fear and Terror?