Good luck but be warned. Mandokir still hits like a truck on steroids. If you kill raptor first he'll hit even harder for a bit AND he has a mortal strike. Meaning you're wonderful instant cast maelstrom healing wave can be cut drastically short. I'm also 10 man Naxx geared and the fight is a difficult one even with a MM Hunter.

I've personally found Tiger boss to be extremely easier, but I do run with a friend.

Just did Mandokir on my 79 blood DK last night. I'm in mostly quest/rep gear, mix of tanking and dps plate. It was challenging, but not impossible. The two minute enrage is rough, but otherwise the raptor will stack sunders that will destroy you. I've heard a lot of people suggest not attacking him during the enrage to avoid eating his focused attack (w/e it's called), but I found as blood spec I just healed through it.

GL on getting a mount :)

I'm not sure of a enh shammy soloing ZG but I do know for a fact a fury/prot warr can easily so all of ZG and even farm attunmen in kara for the horse as well. And since you get instant heals as a enh shammy I would see no problem in farming them except that it will take awhile.