Hi Rob, I'm going to take a bit of time and explain springs as I understand them, but I'd like to qualify my comments with the cavaet and disclosure that I'm not a university-educated automotive-engineer, just a reasonably intelligent and extremely enthusiastic amateur, so I am prepared to be corrected by, and learn from, anyone who knows better...
However, cavaets aside, as I understand things, spring rates are in pounds per inch, lbs/in, or in metric countries KG/cm, sometimes kg/mm. The spring rate units often get shorthanded to simply their mass, with the distance part of the unit getting ditched in the interest of brevity. So we could talk about going from 133lb to 150lb springs, when what we really meant was we replaced our 133lb/in springs with 150lb/in springs. What these numbers, particulary with the suffix to their unit name mean is that a 100lbs/in spring will compress 2" for 200lbs of force applied to it, not that the spring can support X number of lbs/kg.
We all know that if you put a heavy load in a vehicls, it's ridehieght will drop, and I believe this is what happened, on the left side of the RRC, when a lot of gubbinses were moved over to the wrong-hand-drive export models. To adjust the ride height of a car, even on one side, to compensate for the aforementioend lean, there are two ways of making it sit higher, one is longer springs of the same rate, t'other is same length springs of higher rate. After the weight is on the springs and the vehicle has settled, the vehicle with the longer springs of the lower rate will still only need 100lbs of force to compress the suspension / lift the wheel by one inch, vs the (hypothetical) 200lbs required to do the same on the vehicle with standard length but higher "poundage" or spring rate.
So, by keeping the spring rate the same, but fitting longer springs to the left hand side of left hand drive vehicles, Land Rover were able to keep the ride characteristics / suspension "stiffness" the same as the RHD vehicle, while "suspending" the increased weight on the left front corner. Had they gone the other way, and increased the spring rates but kept the coil lengths the same, while the resultant ride height would have been the same, the vehicle would have ridden more like a hot hatch, and worse than that, it would only be stiffer on one side of the front axle, creating some very "interesting" handling characteristics.
I'll stop there, lest this become a wall of text, but I hope I've given you enough information to model this in your mind. If you'd prefer to "see it" than read about it, I'll knock up some diagrams for you.
