Never in a million years will an engine that is modified and set up correctly wear any faster than a standard one.
The majority of people who modify motors have no experience or listen to advice that has no proof or fact at all behind it and the engine they are working on is not in very good order to start with,
Also if a standard land rover motor was any good to start with why does everyone want more power out of them. They are bullet proof I have spent a long time designing the kits I run and have proved the engines are not at fault for the lack of bhp it is just the way it breathes and the way it is set up.I have over 20 years experience with the motor industry and turbo design so trust me I know what I am talking about I Have not even had to change a leaky gasket or add a drop of oil or water in mine.