not a lot is known about the duratecs so maybe type it into google to see if theres any info
xe has the most power out the box but it needs a pricey bellhousing and it doesnt have a dizzy , so it would need an ecu of sometype , if your good with electrickery look into the megajolt kits , the good xe lumps can cost a few £££ too
zetec will bolt straight onto a ford gearbox and all the conversion stuff is readily available from places like retroford ( dave colledge ) this can be run on the original ford edis stuff with a bit of tweeking , all the relevant stuff can be sourced in a scrapyard or even buy a mk5 escort which will have most of the bits needed , give dave a call and see how much his water rail , alternator relocation stuff etc currently costs . http://www.zetecescorts.bravehost.com/
they will all need an exhaust manifold costing around £200
id go for a zetec , but then there is one sat in a mk2 outside the house