In this fanfiction, I think Naruto would win. He has that never - give - up attitude. Even if Sasuke has the Sharingan, Naruto's ability to improvise in battle and his strong bond with his friends could give him the boost he needs. He might be able to come up with a new strategy on the fly, like using his shadow clones in a more creative way to outwit Sasuke's Sharingan - enhanced attacks.
It's really hard to say. Naruto has his incredible stamina and the Rasengan, which is a very powerful jutsu. But Sasuke has the Sharingan which gives him an edge in combat. However, if Naruto has been training hard and has some new tricks up his sleeve, he could potentially win. But Sasuke's determination and natural talent also make him a strong contender. So it could go either way depending on how the author writes it.
I believe Sasuke would win in this scenario. During the Chunin Exams, Sasuke was very focused on becoming stronger. His Sharingan allows him to quickly analyze Naruto's moves and counter them effectively. He also has a more refined combat style at this point. Naruto, while powerful, might still be a bit too reckless. Sasuke could use Naruto's over - eagerness to his advantage and land a decisive blow.