Been quite a few years since I had one, but I believe the easiest route is a 2.0 silver top, fitted with a 1.8 Escort oil pump, oil pick up and sump. Use the exhaust manifold and inlet from a 1.8 Escort (with 2.0 Mondeo throttle body) and i think you can swap a couple of pins around in the ECU plug to run it on a 2.0 Mondeo ECU. It has to be the right code though. DESK rings a bell. there used to be guides floating about on doing the pin swap.

EDIT: It is DESK, just found a picture of the ECU that went into my old 2.0 MK6 saloon.