And what proof do you have to back up that statement that Naruto's body flicker is greater than Sasuke's. Was it stated in a manga panel, interview, anywhere. No there is proof that Naruto's footspeed as an adult is equivalent to that of Sasuke's.
Here
You must be registered for see images
Hell no, Sasuke could not come lightning fast clashing with an Oosutsuki back then. That feat is not equal to the part where Hebi Sasuke caught Naruto off guard. Sasuke's speed keeps increasing throughout the manga but keep in mind his dojutsu doesn't increase his speed, it's his training.