For GB7, Farm 4-5L (Or was it 4-4L?)
There's a large amount of trolls in the stage, and you just escape the prison, and kill/wake up every single troll, and keep doing that. You'll get a GB7 every 1-2 runs at least.
Or you could farm rogers and turn in map pieces lol
GB8, farm 5-1L. Constant respawn