it will be trickier than you expect to get hard and fast ranges for the MR2 especially. The MK1 was a pretty clean beast and also we used to transit a great deal at FL370 up to FL390 and few times higher.
Following a renegotiation of military use of oceanic airspace circa mid eighties, it became pretty standard to transit at FL250 or lower, which knocked the range back a ton. Also the MR2 had a plethora of extra aerials and ducts, which probably didn't help the drag factor a whole lot. Finally as the old lady started to creak at the seams (pun intended) there were often fuel tank restrictions.
Bottom line. Nine hour sorties in the seventies in a mark one were completely standard (I have dozens of them in my log book, and there was no air-to-air refueling before the Falklands. Post Mark two I never flew a nine hour sortie, unless we were refueled in flight.)
I managed 8 hours 50 in a direct transit from the Canary Islands (yes, I do mean the Canary Islands, not the Azores!!!) circa 2000. We had a rescue callsign, so we lied to Shanwick and got up to FL390 ish. Quite funny seeing the reaction of the crew to fuel burn figures they had never witnessed before. We were supposed to refuel at Gib...went straight by....then St Mawgan...nope not stopping, did it in a oner with fuel to spare.