My opinion is 27k unbuffed is enough to clean the 3.0.x content ( hp wise ) , and i see you have gemmed parry .
I've been roaming on forums gathering info and such . What i have gathered is firstly that gemming for parrying actually is rather bad , rage wise but also it is a stat that costs alot , and well actually is less viable than defence or stam .
All this is in my point of view , and do feel free to correct me .
I havent gone to Malygos 25 yet , and it is the only encounter i havent tanked . I love tanking nowadays , and my gemming is honnestly focusing on my threat/dps rather than my avoidance ( due to the "difficulty" of the fights )
If i were you , which i am not =) i would gem hit/expertise , to get the two soft caps at least . Keep enough stam to be above 27k and , ( this is what i do , not liking to gem avoidance atm ) then gem Strength .
This is my wow armory link ( The World of Warcraft Armory ) my gemming isn't perfect due to lack of gold . same for the enchants :x but should be good soon