All CB450's from prior to 1982 you mean.
The DOHC 450's were made from 1965 to 1974. The CB500T were followed from 1975-1976.
As far as I know the 3 valves CB450SC was not made until 1982. This is a completely different animal altogether and shares no similarities with the earlier 450's at all, well other than it has 2 wheels LOL