You have a very late 71, a cam breather 20M3S engine.
You have a breather hose on the left front of the engine...
72 start with 200001 and no breather hose on the cam.
71 are a good bike except for the usual 71 side stand mounts which is a 1 year version, that you come to not appreciate.
The body work could have been any 71 style.
Yes you can get ID plates, but there are at least 5 versions.
The availability of ID plates is allowing bike of questionable origin to circulate. The engine #(last 6) would match the frame VIN plate and gearbox #. There is a frame mfg date only seen by removing the left z plate which should be no later than about 7-71 if it matches the engine vintage.