In my honest opinion mate PHP-Fusion is a great CMS and good system to use for clans. I had Fusion installed as my clan website/cms once before though the only problem with it is the fact that there aren't many good themes or styles to choose from nor are there any good addons.
As for the integration of PHPBB3 into Fusion well I wouldn't recommend it as the code in PHPBB3 is all cluttered and would make the whole system insecure though since Fusion already has a decent forum system with the package I don't see why you would want to integrate PHPBB3.
Joomla on the other hand? It's okay ish and you can integrate PHPBB3 with it if you opt to go down the bridging route.