hiya stu having been a mechanic for the last 37odd years i feel i know rangerovers quite well and the porous block horror stories that are bandied about are not quite a common as some would have you believe its not just the 4.0 that can suffer its also the 3.9 , 4.2 , and 4.6 an example of this scare mongering is my present rangerover a 97my 4.6 which i bought 4 mths ago with overheating problems the garage the previous owner used told him the car had a porous block/heads the cost to repair around 3/4 grand !!!!!!!!! , not so, a quick test with a combustion gas detection kit on the cooling system revealed no combustion gases present in the coolant , the problem was if fact quite a common one where the bleed off pipe from the top of the radiator to the header tank had become blocked at the header tank end literally 5 mins work , result a very well cared for and relativley low mileage hse at a bargain basement price .
i have owned various rangerovers over the last 17 yrs 3.5 , 3.9 , 4.0 , 4.2 , and of course my 4.6 and never in all that time have i even had to do a head gasket on any of them , its my belief that as long as they are maintained and oil changed on a regular basis and the coolant strengh kept to its recommended level then they are no more or no less troublesome than most other vehicles on the road , best advice i can offer though tbh is if your not familiar with the p38a rangerover then get it checked over by someone who is besides the tidy well cared for vehicles out there there are also the tarted up dogs , buy one of those at your peril mate itll empty your bank balance quicker than you can spit , and unless you loaded then i would also suggest considering a multipoint lpg one then you can run a champagne car on beer money costs.
rick.