I doubt that Rinnegan will be overpowered if you seperate the paths that players are able to choose, so there are 6 paths, but the player is only aloud to chose one of them. Seems balanced
I wonder is Haku's Kekkei Genkai is going to be added, would love to try it out, and I like the idea of adding in custom Doujutsu's and Kekkei Genkai's