Listen Naruto's Flash step moves at roughly the same speed as Minato's base speed which earned him the name Yellow Flash right? But Minato is said to be far better at using this speed than naruto is, so naruto isn't faster or more skillfull in that department, Then While Naruto has far more brute power and more variations of the Rasegan, that is useless if he can't Hit his target, in the even that Naruto does catch him somehow, Minato always has FTG which will take him out of danger, without wasting any of his chakra, while Naruto's defenses are much higher in KM that doesn't make him invincible, that would be absurd, also it is shown that even Orochimaru knows how to reinforce the Kyuubi's seal and it is well known that Minato is better at sealing jutsu than orochimaru so minato could easily come up with a seal just as effective or even more-so than Orochimaru's, lastly because Orochimaru used a odd numbered seal placed over an even numbered, it not only sealed off the ninetails' chakra, but it stopped Naruto from utilizing his own properly so when minato does the same to naruto that would also stop him from entering sage mode, so it would be base naruto vs Minato and Minato would dominate easily, with his utter overwhelming speed, FTG tech and Rasengan's Naruto is going to get owned within mere moments