I was only referring to the CB750 models in the USA. I usually go by this list below. I understand the 69 was only referred to as K and the 70 was the K0
SOHC
The single overhead cam models were produced from 1969 through 1978.
1969 CB750K or CB750K0
1971 CB750K1
1972 CB750K2
1973 CB750K3 (US-only, K2 elsewhere)
1974 CB750K4 (US/Japan-only, K2 elsewhere)
1975 CB750K5 (US-only, K2/K4 elsewhere), CB750F, CB750A (Canada-only) The 1975 CB750F had a more streamlined look, thanks in part to a 4-into-1 exhaust and cafe style seat with fiberglass rear. Other changes included the use of a rear disc brake and a lighter crankshaft and flywheel.
1976 CB750K6, CB750F1, CB750A
1977 CB750K7, CB750F2, CB750A1
1978 CB750K8 (US-only), CB750F3, CB750A2