I kind of want to say, gear and builds go hand in hand... But if you want to change your build to go with the gear you have, swap out Energy Armor or Magic Weapon (whichever gives you the smallest paper DPS boost) for a more passive source of Arcane Damage. Something like Arcane Hydra's (for damage) or Black Hole (for CC). That should give you some extra procs off Tal Rasha's. And maybe replace Unwavering Will with Dominance or Audacity (If you're standing still while using Archon... you're doing something wrong ;-)
Worst advice for T6 really. At T6, you don't wnat to lose the stupid amount of survivabilty EA - PA gives you. You just don't. Deflection is also MILES better than Dominance, since it procs of you doing damage, and not relying on stuff mucking about to be killed. If you have a singel elite pack that isn't an illusionist one, you won't have any shields and your raw mitigation will need to soak it.
Unwavering will is "only"a 1.5 second perion. Archon is a Cooldown you use to do burst damage, not kill trash (well, some to quickly build stack), but otherwise, you will be quit stationary when nuking the mobs you want dead. I'm not sure I'd ever want to leave it out. I'm sure there are exceptions to this rule, I'm afraid I haven't found the gear to drop the passive yet though.
If you're flying solo a lot, using the enchantress will probably solve your arcane meteor problem and give you the 4th stack of elemntal exposre. So far, your build looks fine and if you say you can fairly comfortably do T6, good for you. I sincerely do not know how you pull it off with the low amounts of AR and armor, melee and ranged reduction and reduced damage from elites you have. As stated before, I'd try and go for a set of Aughild bracers and shoulders. They can roll very nicely and with the RoRG, you can net the 3-set which is a big mitigation boost.