Bm naruto firepower is too much for itachi.
Naruto can dodge amaterasu and can avoid itachi's genjutsu. Itachi would have to put up susano from the start of the fight due to naruto's speed, itachi's clone would be useless due to naruto's sensing. Itachi has not shown using two ms jutsu at the same time keeping up susano means he can't use the other ms jutsu, if bijuu mode naruto can treat the bijuus like a rag doll then he can do the same to itachi even more since itachi's susano is slow compare to naruto bm avatar and won't hit him. Naruto can end it any time with either mutiple bijuu dama or his big bijuu dama, yata mirror won't be able to defend against it since it only defend the front while bijuu dama will explode, encompass and destroy susano from the back.