Okay, this fight is a little difficult, but having a fair amount of knowledge for both Hokuto no Ken and Eyes of Heaven, I'll provide as many points as I can:
-I personally believe that Kenshiro can at least sense SP. In multiple descriptions of Stands, it is stated that they are a representation of the user's fighting spirit, which is basically ki. Whenever JoJo Stand Users summon their Stand, they are surrounded by an aura. Hell, Jotaro FLEW using his, exactly like how Dragon Ball characters use their ki to fly. Now, Kenshiro fights by relying on sensing his opponent's ki several times in Hokuto, even having his ki clash with opponents like Raoh. Now, do I think that will allow Kenshiro to touch SP? No, not at all. However, I think, at minimun, that he should at least be able to know that SP is there.
-If the speed is equalized, that doesn't mean that their reactions are equalized, so even if Kenshiro gets past SP, even making him disappear with Soryu Tenra, Kenshiro can't touch him, but Jotaro can't hurt Kenshiro at all with just his fists.
-Star Platinum Over Heaven and his ability to change reality by punching it was a last minute ass pull in the story of EoH similar to what happened with time stop in Stardust and the only reason it is used is to justify being able to hit Dio in the final boss battle. Plus, you can play as Jolyne in that fight and beat the shit out of HA Dio with Stone Free, who definitely can't pull the "same type of Stand" bull. So yeah, in character, Jotaro uses the reality-warping thing once, to block a punch from The World OH in a cutsene.
-I don't remember Dio healing himself in the game with TWOH, so I don't think Jotaro can do the same thing, so if Kenshiro manages to hit him, I don't think he can stop the damage from happening.
-When Kenshiro goes intangible, normal ki can't touch him. Only one specific "evil ki" from Kaioh could negate it, but that was really plot convenience. Point being, based on my earlier argument, SP shouldn't be able to touch Kenshiro once he goes intangible.