I honestly think that considering engine displacement alone is a poor measure of a motorcycles highway suitability and ‘highway’ is a relative thing, worlds apart if you live right next to 401 Expressway or Pacific Coast Hwy#1.
Say you’re traveling from Montreal to Detroit, do you need to pull 80mph to pass a transport truck that is spilling gravel or spewing chunks of retread down 401? It’s either that or drop way back and get ready to experience traffic tailgate and imminently faced with second hand road debris.
A full fairing and sportbike rider position makes more difference in the real world. Wind is the greatest enemy for sustained highway speed and if you are wind slippery like a Ninja significantly less HP is required. Legal speed yes, but if you ride with arms splayed and pant leg parachutes, a 250 with tall bars and highway pegs will never pull 80mph passes.
BTW, it’s a demonstrable fact that a standard bike with a handlebar windshield is actually slower than a naked bike with the rider tucked in.
…alas, I have to go plow snow now 
