Re: ssj4 Goku vs. Kenshiro
SSJ4 Goku is too quick and powerful normally. Musou Tensei would cause him problems, since it's not speed based (though it does allow you to move at incredible speed) it creates an illusion you can't see through and thus you intangibly move to attack all around the opponent. He would need ki moves to stop it, and you can't sense the air or ki from it otherwise.
If you take away the weirdness of Musou Tensei, then SSJ4 Goku is clearly superior physically. Kenshiro can hit waaay above his weight because of pressure point strikes, but SSJ4 Goku is too much.
Now about his feats, you have to remember that DBZ has always had piss poor lifting feats compared to it's striking ones (which are above Ken's). Unless you count ki lifting, of course.
Even still, by the time you get to GT, Goku can lift more anyway, and he's been able to strike harder since early DBZ. SSJ4 Goku didn't struggle with the building. What was odd was that his base form wasn't sufficient, so he had to turn SSJ4 which easily lifted the building, and people also forget that he lifted the whole half of that city back into place after that. He could be lifting over a billion tonnes at that point, and at least many millions. Kenshiro is a thousand tonner in lifting.
Adult Dragonball - Early DBZ Goku would be more like a match.