Our clan has reached it's max of level 50 with 12hours xp and a token which we think should be able to carry over to black ops 2 as we can't get any further.

MiasmicTitan. If you look on wikipedia for "prestige mode", under the black ops 2 section it does in fact mention the existance of Prestige Tokens alongside the Unlock Medals.  Two seperate items.  So if your clan hit level 50 it may be worth while to find out if a clan-wide prestige token does carry over.  However seeing as all clans will start at level 1 in Black Ops 2, I doubt it.  So far everything is seperated between MW3 and BO2.