Sakura would be a dude because she's an horrible girl character and i don't like her look as a female, Tsunade won't be her master but Kakashi would.
Ino would be a doctor and Sai's gf because they are a couple of weirdo and they are both super hot.
Gaara would be a girl because damn he would be the perfect heroine for this manga and a perfect best female friend for Naruto imo, maybe like a twin sister.
Jiraya would have something with Tsunade before dying and she will not regret it because ero senin is cool and well, basically she's single and her ex is dead!
Choji and Kiba would be super popular with females, i mean damn when he was fitter, he was just so hot and Kiba is like wine, the older the better

Kaguya would talk for herself instead of saying nothing!
all the biijus will be free for real but still, they would help their old partners and friends.
Lee would have a better role in the manga, idk but he could be a good training teacher for the kids, he's so brave!
Madara would stop talking like a cray-cray zombie and stop being so hysterical about his ex buddy the first hokage coming back too.
it's disturbing like he was fangirling too much about his old nemesis, man control yourself please