Agrees with ElCheapo. The 1975 was the peak year for the 750 SOHC in MHO. First year of the large (cleaner/better looking) winkers. A beautiful Blue color that has yet to come back, or be matched. Dependable from front to rear. All refinements pretty much squared away. Same bike in '76, but color choice was poor.
From mid 1976 on... was a major engine change from heads, transmission parts, to a carb change in '77.
1969 came out with the individual carb adjustments, and large ugly side covers and tank. From '70 to '74 were subtle changes improving the model up to mid 1976. From there on, it's all down hill...IMO.