Defender / Discovery 200tdi Differences

I'm thinking of getting a spare engine to build up ready for when I have trouble with my existing unit. I currently run a Defender 200Tdi in a 90. Can I get a Discovery 200Tdi engine (cheaper), change the ancillaries over and fit straight in, i.e. is the block the same for both engines?
Thanks

Yarp.

^^ as above. Yes you can use the disco block. If you want to do it properly then change the timing case aswell but you can keep it u'll just have to make a few changes though.
Its not difficult to swap casings so i'd do that. Keep it original.