Hello Dom,
several years ago (about 7 or 8, I'm guessing) Peter, who was the P6 News editor at the time, told me that only 27 series 1 V8 models were recorded at DVLA but I'm not sure how you make that enquiry.
James Taylor in his book on the Rover P6 reckons that 16,986 were made for the home market.
Hope the car is still going well for you.
Colin, you may not know that Dom purchased my Three Thousand Five LRV501G about 2½ years ago!
Regards, to you both, John.