This is really simple.Putting a 2.0 into a Fiesta mk3 is a job that can be done in a weekend if you know what your doing. The 2.0 engine will go into a fiesta easily...

Parts needed from the 1.8 Zetec engine as found in Fiesta mk3's/Escort's.

* zetec engine mounts from fiesta 1.8 XR2i's/GTi escorts.
* sump and oil pickup / sump tray from the 1.8 Zetec engine.
* Oil and Water pumps from the above engine again.
* Inlet manifold from the 1.8 Zetec again.

Getting a donor car will really help as you can use the radiator and you will have the loom and ECU already to hand. If you dont have the loom to hand you can use the fiesta xr2i loom or the Fiesta Si 1.6 loom but you can only use certain ECU's, DEEP is definetly one you can use as i'm going to be running that in my 2.0 fiesta eventurally.

oh and heres the list of other things i had to change...

1.1 fuel lines dont match to the zetec engine so needed zetec fuel lines from my xr2i,if you intend on swapping the power steering or something from a mk3 to a mk3.5 you need to swap the hubs,driveshafts,track rod ends as none of it swaps over from mk3-mk3.5 *that was fun to find out mid conversion*

Oh and if swapping hubs SORRY but mk3.5 suspension wont fit in mk3 hubs properly so the whole lot needs to be swapped over.

A problem I had with putting a zetec into a mk3.5 that had a 1.1 engine is that the chassis legs didnt have the captive nuts in them to mount the Zetec engine mounts.Check this first as you may need to get them welded in or find another way to fit the mounts...I just welded mine onto the legs and no issues so far lol

I hope thats helped somewhat. 2.0 zetec is 128bhp out of the tin so its a WIN in my book.