as I understand your goal is todoay UBRS with 7 charakters, with a melee team WWWWS.
I dont think Drakkisath will be possible with an further player who kite drakkisath.
Beast should be doable with decent gear.

Mixing a melee team with mana dd cancel the advantage of less downtime for drinking.

x) I would add a Feral Tank and a Healpriest.

group1: Feral Tank - W - W - W - S
group2: W - P

one healer till rend is enough, after rend a 2nd healer is useful
for rend event you can let your shaman spam lightning bolt if you need further damage

x) another option if you only want play with one healer, then I would add a Feral Tank and Enhance Shaman or Rogue.

Enhance Shaman - emergency heals, all get totems, totems are a little stronger,
Rogue - more damage, poison (slow for runners or casting speed)

x) a further option would be not playing melee cleave, then I would add 2 more mages to your current setup.
3 mages spam firebolt, 1 mage spam scorch, pulling with 4 pyroblast