from a 69.3 chest drop has a 980 fire-based nuke with a 2s cast time.
from a 69.2H chest drop has a 1100 magic-based nuke also with a 2s cast time.
However, they both are on recast type:3, so I assume they are on the same timer. Unfortunately, with a 720s recast (12 min), you're not gonna get much of a DPS boost from them over time.
To get the most DPS from your shaman bot, I'd suggest thinking like a shaman and not a nuker. Before Sting, shaman are not excellent nukers -- our nukes are pathetically weak and inefficiently expensive (our rains are passably strong and efficient). This means stacking DOTs is your best bet. This also means any Affliction Efficiency and Burning Affliction items will help you
a lot with mana savings and damage done. You can tribute these until you find the gear for them.
If you're old enough to get Lingering Sloth, keeping that on your warrior will allow you to stack more damage with your shaman before ganking aggro from him.
If you can manage it 3-boxing, cast panther on as many targets as you can -- have your shaman melee, your cleric if mana regen is not an issue, or at the very least, get into the habit of casting your cleric's pet hammer and panthering it for another source of efficient DPS. Summoning puppy pack every 15 minutes is a mana-free source, and also a good way to do burst DPS when you need by also panthering the puppy pack.
Aside from keeping panthers up and haste on your warrior and on your pup, giving your warrior as much DS as you can can also help with DPS. stacks with , giving you 80 in DS on top of any worn DS your warrior has. And don't forget your cleric's reverse DS for another 45 in DS ().
But above all, keep mashing that canni button as soon as it pops. That's your best source of power right there