Use caldanis despair on all items, and switch all diamonds to topaz. And head to +23% hp. You dont need that extra toughnes for gr 70.
Even if you just use 50 gems that should net you somewhat around 2K int. 70 should be easy. If you still feel squishy switch stricken to esoteric. Ive similar gear to you and 100 extra pagon levels and im speedfarming 70 for gem upgrades
1) You have no area damage on your gear, this is HUGE for gargantuans. Unfortunately you can't re-roll anything obvious on existing gear that I can see.
But I would recommend AD on at least the shoulders and one more item. +skill to gargantuan on shoulder, chest and mojo is good but I think AD is better since skill% is addative with MoJ. (don't forget to recast gargs in the middle of the packs so AD/cleave is most effective)
2) Get a new amulet with CHC/CHD/INT/socket, the secondary on Ouroburos isn't _that_ good.
3) Since you didn't roll off the socket on the weapon and use a gift I would highly recommend trying to get a better weapon as well.
4) Your gloves are also sub optimal, if you have better (at least CHC/CHD/INT) helltooth gloves, consider checking your inventory if you can run with HT-gloves and MoJ equipped and cube the Taskers.
EDIT: ran some simulations in http://www.d3planner.com/ on your character seems like +gargantuan -> AD on shoulder+mojo is a very good DPS choice for you, 470B -> 538B :-)