You could easily tank ulduar 10 as is and probably ulduar 25 although probably changing your block pieces would be better. The old target was 32K unbuffed and 55% avoidance and you are very close to that.
Personally for me change the neck to the conq badge one thinks its only 19 badges from memory and I would get the platnium mesh cloak for back which would ease up some +20def gemming you having to do and your could change to hybrid gems and gain a bit of extra HP.
The libram yeah but really LOO isnt going to worth huge amounts in ulduar so thats an optional you might just hang out till you get triumph badges.
As for the shield its a block set trash shield it stays in the bank.
Go kill the brewfest boss for your +170 stam trinket to replace the essence of gossomer the shield effect isnt worth much in ulduar.
Tank ulduaar collect loot move on ... GL
** Remember Warcraft players fail in directions you never thought possible.