I ran a 6.0VXR for a short while. The motor is totally awesome - properly big grunt from anywhere in the range and a wonderful noise with the loud exhausts.
However, I sold it & carried on with 260's, as the Monaro feels wide, soft & baggy compared to the hard nut MG which is just so unbelievably well suited to UK roads if you like driving a bit hard.
Each to their own, but to me the Monaro is built for monstering long straight AUS outback roads and the 260 to our uniquely varied & twisty UK tarmac.