As there is a very slim chance that someone else may have had the same idea as yu. HAve yu considered using Google (other search engines are available)
In summary the Disco 200tdi goes into a 88" but the turbo will foul the chassis on a 109". If you want to keep the turbo, then a 200tdi from a Defender will not foul the chassis on a 109". The engine bolts to the series gearbox with a little modification (drilling and tapping), the bulkhead does not need to be modified. The chassis on a 88" does not need to be modified, original chassis engine mounts can be used. The engine mounts from a 2 1/4 Land-Rover engine can be bolted straight onto the 200tdi block, but some spacers to lift the front of the engine would be a good idea. The battery will need to be repositioned (under the passenger seat is a good spot). Installing the engine without the turbo would be much easier because you will be able to use the series rad, air cleaner and exhaust system and the nearside wing and radiator panel will not need to be modified, but an 88" with the turbo and intercooler goes like stink!