Reaction speed plays part in the speed of the overall character. It doesn't make sense for it not to be.
You just want it to make sense, that's all. Although it doesn't.
Foot speed wise, Naruto = Sasuke should be in the same era.
Naruto is the leader in footspeed. Although Sasuke is extremely fast, and almost equal to Naruto is footspeed, Naruto is still a tad bit faster, though not a very big difference.
Shunshin speed, does not fall in the category of foot speed. Naruto is faster.
Shunshin speed may not fall in the same category, but it adds to Naruto's speed. And since Shunshin relies on footspeed although it's technically different, so it makes Naruto faster than Sasuke overall in footspeed alone, since that is evidently footspeed.
Teleporting is in a tier of it's own, which Sasuke sits comfortably in.
Yes, and S/T >> Shunshin. Even Naruto's footspeed added with Shunshin won't compare to Sasuke's footspeed added with inferior Shunshin and incomparable S/T. Sasuke is manifestly faster.
Reaction speed, Naruto takes comfortably.
Okay, but it's irrelevant. It only helps in body movements, not in covering distance.
These all play crucial factors in the "speed of a character"
Naruto >= Sasuke (footspeed)
Naruto > Sasuke (Shunshin)
Naruto <<< Sasuke (S/T)
And S/T >> Shunshin
Sasuke > Naruto (overall)