I don't even have a resto specced shaman and I cleared UK fairly easily with a 70 DK and 4 70 shamans.

First off, how is your pally geared? The only reason it was so easy for me is because I bought my DK the entire "cobalt" tanking set (level 70 crafted green plate) which is almost entirely str/stam/def. This gave me something like 470 def at level 70, 12.5k HP, and 14.5k armor. This is with neck/rings/cloak/etc from outland (greens and blues).

Sounds to me like your pally is undergeared. With 3 mobs my DK hardly had to be healed at all, with 4 I usually had to heal once and thats it. I just use 4x lesser healing waves to heal my DK, no dedicated healer.