How to Get the East in Full Communion with Rome
What would it take for the West to be in full communion with Rome?
I think you mean the East, specifically the Eastern Orthodox vs. Eastern-Rite Catholics, vs. the West, which is in full communion with the Rome, despite some irregularities in dioceses around the world. A key requirement would be the recognition of the pope as having God-given primacy over the universal Church regarding teaching and governing.
For more on this subject, see this Catholic Answers Magazine article by Fr. Ray Ryland on “Frank Dialogue” and this one by Fr. Brian Harrison on why he became Catholic and not Eastern Orthodox.