I've not done it myself, but a bit of minimal research shows :
* Capacity : 2993cc
* Configuration : 60 degree V6 Pushrod OHV.
* Cast Iron Block and heads
* 93.66mm Bore x 72.44mm Stroke
* Power : 136 BHP @ 5000rpm
* Torque : 174 lb-ft @ 3000rpm
The obvious comparison is with the standard Rover V8 (let's assume a 3.5).. depending on what it was built for the specs will vary quite dramatically, but if it is a std engine for the vehicle :
* Capacity : 3528cc
* 88.9mm Bore x 71.12mm Stroke
* Power : 127bhp @ 4000rpm
* Torque : 194lb ft @ 2500rpm
The biggest issues I can see from that are :
1) The V8 is possibly going to be heavier than the V8 since it is all cast iron. (Although this is a Range Rover we are talking about so the percentage of weight is probably not huge !)
2) The V6 is down on torque compared to the V8, and that could cause issues in such a big vehicle, especially off road
3) The V6 has higher power output, but it is at higher revs, so the engine will be working harder for the same apparent performance
I'm sure it can be done, there are plenty of them in Series Land Rovers, in which the conversion seems to work pretty well. For my money though, in a Range Rover, the V8 will be a better power plant
