I would've toned down the powerscaling and changed some things in the Buu Saga.

• First of all keep SS2 Kid Gohan and Cell stronger than everyone at the beginning of the Buu Saga. Goku and Vegeta are still only able to access the regular Super Saiyan transformation and Gohan is unable to call upon his true power at will due to his lack of training and because he could never call upon it without being angry anyways.

• Replace Goku's SS3 with SS Kaioken. This way it doesn't come out of nowhere, has an established reason for why it strains Goku's body so badly, and explains why Vegeta didn't achieve it despite training as hard if not harder than Goku. It'd also allow him to be the strongest without actually being the strongest at the same time.

• Replace Gotenks's SS3 with SS2 and make it so that he's only as strong as Gohan was when he fought against Cell. Make it so Super Buu is at the same level.

• Rather than Gohan's Potential Unlock making him way stronger than he was as kid for no reason, just have it allow him to tap into his full power that he tapped into for the father-son kamehameha at will without needing to transform. He'd still be stronger than Gotenks and Buu and now his power up would actually make sense instead of just coming out of nowhere.

And with that the arc would stay basically exactly the same except the power scaling would be much cleaner. Goku and Vegeta have seemingly hit their peaks and the promise of half saiyans being stronger than full-blooded saiyans is fulfilled. Then with DBS you could introduce God Ki as a way to power Goku and Vegeta up letting them surpass their limits and it'd also cut down on the silly amount of transformations each of them has and would explain why they never use SS2 or SS3 alongside SSGSS.