Did you have a "barber pole'' on the ASI (Air Speed Indicator) to denote the changing Vne values, (what really was Mmo, I guess) or did you just have a look-up table in the Constellation and the DC-7?
No barber pole on the 1649 or DC-7 (nor Stratocruiser, which was in the same category of high altitude flyer)...you had to make corrections manually (table), if necessary.
It was rarely a problem however, as normal descent speeds were operationally lower.
The Lockheed Electra had one however, as that airplane, as originally certified, could outrun a 707 at lower altitudes (Vmo limits).