This takes a lot of engineering to make them fit, there is no where for the springs to attach which is the main problem.
Be aware of how much you change, engine gearbox and axles may take you to a Q plate although i am not 100% sure, worth checking beforehand. Do you want to be hammered by the insurance?
Once you have changed all of that you may as well have bought a range rover and modified it for off road. It would be a damn sight more comfortable.