Helped a mate do this to a Mk4 EFi XR3i.

I believe easiest way to put a Zetec in a mk4 is to use an EFi XR3i since both engine use the EFI setup - therefore tank and fuel lines are compatible. Prob best to use the EFi XR loom and then see if the Zetec management loom plugs into it? I cant remember but I will try to find out.

Get some pics up mate.