I geared my pally tank from multiboxing heroics and eventually Kara. It was very difficult for me at first. I remember wiping for hours in Slave Pens (no joke). It seems silly to me now that I ever wiped in there. But that's part of the fun. You really get to see the development and strength of your team as you persevere through those initial struggles.

I have a few raid pieces on my healer now, but those didn't come until recently. I had crafted the Primal Mooncloth and Whitemend tailoring sets that I used during my first stages of heroics.

Good luck to you. The team you have proposed should do well. I hope you enjoy the rewarding challenges of multiboxing as much as I have.