Sir you have mentioned that the frame and suspension is perfect and also looks perfect in the pictures, you have all body parts, the body seems mostly straight just needs some denting and the body is almost entirely aluminium so there would be only minor rust on the non-aluminium components, so why would you even think about a body change?
You haven't mentioned what the engine is like or I may have missed it but I would assume that the engine is fine too, if so I would recommend you to firstly have the whole car thoroughly washed inside out and complete it, i.e. install the missing fenders, bonnet and the front etc so that the car is "loose" assembled and you can actually see what you're working with. In it's current state unless you do restos frequently this project is going to overwhelm you if keep it looking the way it looks right now and then in due course fatigue you out.
Once the vehicle is loose assembled, then look at what your base is like and create a checklist and list of things that need to be done, from the images I see I would say under carriage and frame etc all good, perhaps exhaust needs to be replaced or just rust coated, engine would need some TLC before being started, check replace hoses, fuel and brake lines, caliper re-build all around so the vehicle is safe, complete fluid flush, check rad, repair/replace if necessary, replace all fuses. Now you have a good base vehicle. So start looking at aesthetics.
Identify what areas need to be attended to, dents scratches etc, and also give your LR another undercoat and a rust coat on the inner floor too, I see some of your window rubbers etc are also missing, if you don't already have them stored they should be available, in fact virtually everything should be available for this Defender. Attend the dents and scrapes, get the vehicle straightened out and base prepared. Don't over prepare the body as local paint no matter where you get it done from is almost never flawless and this is usually entirely attibutable to poor prep work. So again, don't over prepare the body, only prepare the parts which have ben dented, rest of the body is all good so just have it sanded to give you a good base for paint, have it bake painted, use Y2K, and thats it, while driving the car tart up its interior, do other minor upgrades if required and you're done.