the T9 4pc bonus isn't great to be honest.
it's a little more emblems, but personally, what I did while gearing was buy the legs and gloves T9, got the crafted breastplate of the white knight, got the 245 non set shoulders (15 more triumph than the T9 ones) and the 245 non set helm (25 more triumph than the T9). you end up with more stats with only slightly more work.
the cloak and shield from HoR normal are both easy to obtain, have pretty decent stats and should last you untill you get a chance to upgrade from raiding.
Trinkets are good. few enchants need swapping (I'm assuming this is because of lower level gear but I'll post anyway). you have a wyrmrest tabard on, yet the tanking helm enchant comes from the argent crusade rep - get farming. the best shoulder enchant comes from pvp, the 30 stam 15 resi gladiator enchant will cost 10k honor but it's worth it.
Get 18 stam on shield (unless you're short on def, in which case get def). It's personal preference, but Blood draining is considered to be the best tanking enchant, the heal when you need it can really help in some cases. you've invested in epic gems for you legs, yet you havn't bothered to get the epic armor kit?
get your proffs leveled up, the stam from mining is really nice and the engineering glove enchant I believe is currently the best EH perk for tanks (plus engi is awesome!) but you should put stam or armsman on there in the meantime
also, you should either pick up Rowen's rifle of silver bullets from the AH cheap, or get blades of the sable cross for 35 triumph.
I also noticed you have more than one expertise + stam. right gem but you should really only gem it once to activate your meta after that just pure stam.
if you have the gold, Pillars of might and Boots of kingly upheaval are very nice investments as you won't replace them quickly (and legs are the weakest part of T10). you say you're "saving up" for spiked death dealers, use the titansteels for the kingly upheaval boots instead, do your dailies and buy primordial saronites, you won't regret it!
for frosts, I personally used:
and finally, to your original question. get the shard of the crystal heart, hope the neck from HoR heroic drops, and then pray from marrowgars scratching choker to drop once you get in ICC (I swear neither marrowgar or HoR necks actually exsist. I've had my 25 KT neck for over a year now with literally nothing better dropping, doing heroic ICC 10 now and still no neck)