I think that the 110 chassis is deeper than the Range Rover chassis as there is a lot more strength in a Range Rover shell, so it would not just be a case of stretching a Range Rover chassis.
Over here lots of Range Rover chassis have been shortened to 80" and 88" for trials motors, but it is not a five minute job.
The parts you would have to weld to the Range Rover chassis are probably the same parts that need replacing on your 110's chassis anyway.
Access is usually the biggest problem when welding rotten Land Rover chassis, so if you remove the body, you will probably find that keeping the original chassis is far simpler.