The original std F2 sprocket in the manual seems to be missing the smaller holes, just has the set of large 8 holes and no face relief.
Thought the F2 had more teeth as std also but can't find a spec for it or it's sister bike the K7, both being the first 750 to have this larger 630 size as I understand.
The wieght reduction suggests a slightly later model and fairly small 38T a bike that has a higher top speed/torque capability than the 750.