Yes, you've done it! The pinnacle of your Tailoring profession, and you're in the home stretch, now. Once again, skip the Outland level 70 epics, and don't look back.

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Level 376-395: Frostwoven Boots, Frostwoven Cowl, and Frostwoven Leggings will bring you this far.
Level 396-405: The Duskweave set of Belt, Cowl, and Leggings gains you 10 levels here.
Level 406-415: Duskweave Wristwraps, available at 400, will bring you up to 415 easily.
Level 415-420: Remember that specialization you took back at level 350? Now you will be able to craft the blue-quality Northrend special cloths. Once every 4 days, make your allotment of Ebonweave, Moonshroud, and Spellweave. Hang on to whichever type you'll be using for your personal set, and trade the others for more of the same.
Level 420-435: The Black Duskweave Robe is an awesome piece of crafted gear, and you should be able to sell these about as quickly as you can make them. As an added bonus, crafting these robes will bring you within 15 points of maxing your Tailoring.
Level 436-445: Gain ten levels by crafting the hand-warmers of your choice, either Ebonweave Gloves, Moonshroud Gloves, or Spellweave Gloves. All of those specialty cloths are coming in handy now, and you want to make sure you're crafting those as soon as your cooldowns are up.
Level 446-450: The final stretch is always a pain, but you can count on guaranteed levels with the Glacial Bag pattern. This 22-slot bag will sell for quite a bit, and you may be better off advertising the crafting when your customer provides his or her own mats.