Are you building an army, or looking for information? Given, that you are asking about squad sizes, I will assume the former.
I would go with the Termie/Scout army: use scouts for troops, and Termies as your main-line troops (and take full-size squads). Plus whatever HQ you want (Captain Agemman, I assume) in Termie armour. As for Fast Attack and Heavy Support, probably just a Land Raider.. or two, depending on points.
Unfortunately, I don't have a lot of info on the Ultramarines. Just the Space Marines Codex. So you probably know as much, if not more than I. Sorry...
__________________ Lord of Fluff and Blood Angels Herald of Nurgle "I wield my power with the Emperor's Authority. Those who would say that I am 'radical' merely have minds too small and impotent to realize all the weapons at their disposal. Do not question my methods on account of these so-called 'Puritans'." -Inquisitor Mathias Rosenadel |