The picture of James bike is a usa F2 (Super Sport) and steve's one is also a F2 UK. If you are looking at a 1976 it should be a F1, it should say on the frame number.
Now i am confused, the link further up leads me to the following
CB550F Serial Numbers
CB550 F1 1975 CB550F-1000002- CB550E-110004-
CB550 F2 1976 CB550F-2000003- CB550E-1109887-
CB550 F3 1977 CB550F-210001- CB550E-1135380-
This indicates the 1976 is a F2
I know nothing, i am learning day by day.
Alan