A lot of northrend is going to be painful, but what you want to do is open up all your quest hubs. This will get you the rest of FPs you don't have and it will open up other quest chains and give you the basic rep your missing. Basically, I'd start in Borean / howling for your Argent Crusade rep, Wyrmsrest Temple in dragonblight for your Wyrmsrest Accord, Ebon Watch in Zul'Drak, The quests for Kirin Tor are scattered all over the place, you'll find them in patches. Those are the 4 you can Champion.