Can anyone help Harry find some history on his car?

‘My car is a 1977, spent 19 years in the USA, before being first registered in the UK, on the 19/02/1996, I acquired the vehicle on the 20/07/2017, The car has currently got 6,500 miles,
I’m trying to find out if this is the original mileage, contacted the DVLA and it only went back to the last 4 MOTs, any information at all will be very grateful. Regards, Harry’

If you can help Please contact Andrew Vigor the MGB Registrar