Its not even close to worth it.....
For $1500 you get an engine, but you still need;
the trans,
ECU,
exhaust header,
engine & trans mounts,
shifter assembly,
have to modify the engine bay to make it fit,
and either have to pay somebody to put it all together or do it yourself.
Minimum another $1000 if you do it all youself.
Looking at $2000 plus for somebody else.
Ot trade in the 4 cylinder, take the $1500+ in cash and get a fully paid for Duratec Contour.
Or get a used SVT Focus or (even better) SVT Contour, and either would be half paid for.
For less than $1500 you can put a stock Zetec past the SVT Zetec #'s.