During the Valley of the End fight wasn't Naruto matching if not exceeding Sasuke even with 2T sharingan? Then when Sasuke developed it into 3T Naruto had to resort to the fox's cloak with only one tail. I do realise that this is a shippuden fight and things have changed, but it was shown in the past that Naruto could keep up with the sharingan without any advantages like sage mode or fox's chakra. Before someone jumps me and says that he only could keep up because he used the fox's chakra for shadow clones, Naruto himself has a large chakra pool without relying on the fox.