Prot paly and 4 shaman.

With the new dual spec patch I suggest you to try 1 prot paly and 4 resto shamans rotating heals.
It's slow as hell, but it's really funny because you can down 10 man raid content with this setup... the overheal is so much that your pally will never die whatever you do.

I tested in on tempest keep trash at lvl 70 just fore the laughs... still not reached lvl 80 with my group, but I guess that it will be not very different in naxx 10