The speedometer was one of those federally mandated things. Cars of that vintage had a limit of 85mph as well. I know my 1979 CB750 has done over 85 mph many times. It'll go faster, I just don't have the courage yet. I'm sure it'll be fast enough for you.
At 6'7", I might recommend some sort of windshield. At freeway speeds you may get beat up with wind.
Hope this helps.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.