Going from a A1200 to an A2000 is a step backward in more then one way. You would be loosing the AGA graphics capabilities of the 1200 and the 1200 also has far more exspantion capabilities then the 2000 has.
Your best option is to get yourslf an empty mid sized tower case and carfuly transfer the a1200 into that. Then you will have lots of room.