I have previously re-chassied a Land a Rover and know lots of folk who have also done chassis swaps with their land rovers, and if your very handy on the spannerís and have a access to a ramp and a full set of tools then itís not insurmountable but still very time consuming and costly as youíll end up replacing lots of parts during the job including every pipe, clip, bush, etc and youíd be as well splitting the box and doing a clutch and lots of other jobs at the same time.
However if your barn doesnít have a ramp or forklift and your doing it on the floor with basic tools itíll be much more of a mission.
Before even considering it you need to fully evaluate your chassis, which has to be in very good condition. If its scabby, pitted or needing welding then the blasting process will likely find more bits and you could end up in a world of pain. If galvanising a used chassis you also really need to get it acid dipped first and not simply blasted, as most galvanisers only have a pickling tank and donít acid strip. As such the paint, coatings, and contaminants on the inside of box sections wonít be removed and the galve wonít adhere, which completely defeats the purpose as the rot from the inside out, youíll also need to drill drain holes in any closed box sections, or they risk exploding in the tank.
Land Rover series and defenders are appreciating in value and are worth doing, however relatively few get their original chassis galved (unless itís in very good condition or has been well restored), and opt for a brand new one and tight L200 isnít worth it unless itís relatively new, and / or you intend on keeping it forever.