Straight swap engine wise, bare in mind that the 2 litre has a larger radiator and also the mtx75 gearbox. Exhausts (including manifold) are identical as are the intake manifolds and throttle bodies. I don't know about the fuel injectors though.

The brakes are the same size front wise the only difference was the 2 litre had rear disks too. The 1.8's did have rears as an option from what i remember. It's easy enough to convert the rears to disks with the 2 litre parts including the hand brake cables.