While getting your aldor rep up is great, you're are 70. If you're close to getting your flyer I would recommend getting it so that you can start running mech if you really want a new chest piece, so that you can pickup Jade-Skull Breastplate.
Not sure if you're quite ready for some heroics yet. But check out this website for a sort of pre-raid shopping list if you will of gear you'd wanna work for Kaliban's Class Loot Lists
Ah yes, thanks Deefe. I use wow-loot.com extensively. I argued last night with our guild rogue about heroics. He swears up and down I'm geared for but personally I think I need to get to 12k Health. My shopping list includes the items from wow-loot and that's what I'll continue to work towards I guess.
My first upgrades would be to grab some of the quested gear for tanking. You need a faster weapon (Grom'tor's Charge) and 3 more defense skill. I used 12k hps/ac to be my baseline for tanking heroics and it worked out well for me, with a similarly geared healer backing me up.
Your socket choices are well.. interesting. I can't find the pattern to it at all. You may already know this, but I'm going to say it in case you missed this.. you can use hybrid color gems to hit socket bonuses. For instance you could use a green def/sta gem to hit a yellow socket. Before you attempt to get the socket bonus, do a reality check to see if it is worth getting. For instance your gloves have a socket bonus of +3 parry rating, which (while being a good tanking stat) isn't helping you as much as sta, or even dodge/def. I personally would decide to skip that bonus and use a +12 sta gem.
I've upgraded quite a few pieces. My chest piece isn't optimal but I've had a hard time getting the Jade-Skull Breastplate or Suneater to drop. I've also regemmed my pieces to try and maximize stamina. I'm up to 11,894 Health and 11,962 Armor. I need at least 6 more points of Def though. Only 484 atm. I'm still working on SSO Rep for the shield.
Don't kill yourself over 490 Defense. Yes, it's very important - but you will get there eventually. It's not the "requirement" people make it out to be in early Heroics. Remember it's not black and white, it's a sliding scale - 475-485 will prevent almost all criticals, and the ones that do get through will not spell the difference between success and failure.
First: SSO Exalted for the neckpiece and shield. Both huge upgrades, and it looks like you're already Revered.
Second: Aldor Revered. You will want this reputation eventually anyway, and the hauberk can serve you perfectly fine until you get the 2.4 badge chest.