'At altitude cruise at Mach 0.85 and even some M.086 if the company requested it. But usually a bit slower, around M 0.82 just to save some kerosene"
The ' hump' for the upper deck helped to achieve a slightly higher mach number due to the famous " area rule " which simply states making the station to staion projected area " curve" as smooth as possible, so the hump slowly provided an increase in the transverse cross section area from the nose to the hump to the wing area. For fighter aircraft it made it easier to power thru the high drag buildup as one approached mach 1.