Makes more sense now. So, as per the original question, its rear lights are correct for its age/model.
I suspect Nissan UK, if that's who you've talked to, probably know jack about it! Whatever the logbook shows, that car is, as Alan noted, a Nissan A-S30 Fairlady Z, most likely a Z-L model, given it has features like the heated rear screen, passenger foot rest, and the rally clock. It's got Datsun in the logbook due to people who don't know any better!
It's obviously been cosmetically fiddled with during it's life, most obviously the dodgy 1-piece aftermarket G-nose (it would've had the standard headlight buckets, 3-piece valance, and mesh grille), and the rear quarter side marker lights (these are not original and would've been added in the US). It's also lost one of it's most distinctive JDM features, i.e. the original wing/fender mirrors.
What are your plans for it? Stock restoration or modified? You mention you've sourced an engine - what engine? I'm guessing not an L20. Many L-series parts are interchangeable but there's still plenty of variation to consider.
Look forward to seeing what happens with this one. I actually considered it myself on more than one occasion. My preferences and available parts pile are a bit more jigged around pre-73 cars though, so I'd be wasting what I've got having to chase later-spec stuff like interior, etc. Still it's an original Fairlady Z, which is cool IMO! Should've had a pop at it six months ago! :lol:
Aside from the manual Alan mentioned, a useful English resource is the Brian Long book, Datsun Z: from Fairlady to 280Z. That covers lots of detail about the evolution of the models, including the JDM cars.
Broadly, it would've looked like this when new: