Difficult and certainly not a 'Drop in job' at least it is with the Zetec engines this is due to the exhaust and inlet being on opposing sides and so this means you need to change the exhaust as well.
The new Duratec 2.0 I think has the manifolds the same so it may be easier, I.E Inlet at the front and exhaust at back as you look, you then need the ECU, reprogram keys etc, and possibly the suspension may need changing as well.
This is just a few things that spring to mind and not an exhaustive list by any means.
Normally people don't bother for these reasons and buy a 2.0 outright.
Have you thought about tuning the current SE engine, 145HP is doable, however it's not cheap, look at Shaw speed for more info.
Martin