It’s all right here in this link. I’ve included a list of items (along with some alternatives). In addition, I’ve created a few tables with relevant priest look from each of the major reputation vendors.
Remember, it’s not a best in slot list. It’s a relatively fast in slot list. The goal is to get your Priest geared up as much as possible to hit dungeons and raids for the real good stuff. I tried to minimize the RNG as much as I can, but ultimately there’s going to be a few elements involved.
Good luck and I’ll see you at 90!
EDIT: If I run into anything on the way up, I’ll add it. I’m sure there’s a few out there I may have missed. I deliberately did not select PvP gear (but you can maybe get away with 1 or 2 pieces if you need to).