Withstanding Drek - Tanking strat/gear/stats

Hi guys I want to know what you think of Drek in terms of strategy.
Do you have experience tanking him?
1. Which protective stats minimum are you suggesting?
2. What stats weighs more?
Avoidance vs Max HP

I feel like Max HP sometimes weigh almost more than the overall avoidance but is that people being lucky not being critted or is Drek's crit fairly low and crushings don't really matter?
I heard that 490 is 'def cap' for 72 bosses (I'm not sure his level but I'm assuming 72) and that crits are no longer possible on the tank when this cap is reached.
On my prot pala I can reach about 504 def and about 10-11k hp but it doesn't feel sufficient, I need heavy heals, pain suppression etc to make it.
I feel like I need kara prot gear to have greater success.
I'm mostly pvping but do you think it's worth raiding kara (time invested) to maybe get a little better gear for Drek?