The Aermacchi 350 P3 roadracer number 107 is mine and was built from a 350sx motor (much modified, shorter stroke, bigger bore, c/r gearbox, big valves, race cam, cr clutch, race ign) all in a modified 62ss frame.
The factory race bikes were different in the castings but you would have to be very fanatical to pick the differences.
Strange where these photos turn up??
JI