Man, what a find.

There is no "VIN" in the sense of a code, 1200s only have a sequential serial number.

The build date should be on the driver's side b-pillar when you open the door.

1971 apparently had a higher compression piston, but that's not proven.

No USA 1200s came from the factory with twin carbs, only the GX models had those. And only the GX-5 came with a 5-speed.

8000 RPM factory tach was a dealer option. 10,000 RPM tach was a Datsun Competition part. Ditto for headers, though more likely they are aftermarket. An oil pan with wings is aftermarket.