Like what everyone else said, get him to respec properly. Drop the priest boots and get something without spirit on it. Drop the shoulders, or at least get the aldor/scryer enchants for them. Drop the spirit ring as well, there are much better options, even the first violet signet. Get a bunch more crit as well.
His healing, crit and total mana may not be sufficient for extended boss fights, especially if he's posted on the tank. I'd say either get 2 other healers with much better gear, or drop him for a week or 2 so he can get his gear in order first. The guide that's stickied would help with replacing some of that gear. I ran kara my first time with similiar gear, but we had 2 much more experienced and geared healers. We still wipefested and only downed attumen curator and moroes after about 3 hours. Subsequent runs got much better though, we usually clear about 8 bosses in 2.5 hours (only if we've got full team 1 though). But yeah. Don't worry though, attumen drops great pally healing gloves. Socket and enchant well and that's as good as 100 more healing already =)