Will fit straight on no bother providing original head is a 1.8, I think the 1.6 head is quite different.
You swap the MK1 mounts to the MK3 block, then you then need to swap the gear off the 2.0 dizzy onto your old dizzy, and fit it using an adaptor ring. There is also a breather on the front of the block, you can buy a blanking plate to block it off.
The last thing to think about is the gearbox/clutch setup. You can either swap a 1.8 clutch & flywheel to the 2.0 and use the existing gearbox, or use a MK2 16v or MK3 rod change box & clutch setup.
Both the adaptor ring & blanking plate are available from TSR I believe
