Quite probably a legit 70/71 targa that. Backdates are often so good it's tricky to tell, but I'd wager it's proper.
Whilst 15x7 Fuchs were around then it's massively unlikely that car was delivered on them, I'm not sure they were even an option, so I'm calling wrong wheels, should be 15x6.
It could only be a backdate if they'd swapped the entire interior, which of course they may well have done.
I loved everything about this car, other than it wasn't mine. Let me guess - £100,000 minimum, and it'd break down every hour and a half?