I upgraded my Fury form a xflow to a Zetec last year. So far it has done about 15,000 miles including 3,500 through Spain and France recently without missing a beat. I don't have a recent picture of the installation so this will have to do. Needless to say it is now somewhat neater as well...
As has been said it isn't cheap to convert a Zetec to RWD, but as with anything there are plenty of ways to save money. Provided there is space you don't need a new water rail (I didn't). If you do need one the retro ford one is cheaper than the Raceline version. You don't need a new flywheel, but the 2.0 Zetec version is a boat anchor, so at the very least fit the one of a 1.8. The blacktop sump is part ali, part steel with the steel bit at the bottom which makes it really easy to shorten. It is possible to reuse the standard Ford induction although that will strangle the engine. The spigot bearing will only set you back about £10...
The reason that I fitted the Zetec over other choices was that I wanted a powerful, reliable (Used only 200ml of oil on the spanish trip

) and disposable engine. If mine goes pop I can pick another up tomorrow and stick it straight in for only a couple of hundred...
The costs of my install were as follows:
2l Engine £200.00
Sump £182.13
Exhaust Manifold £200
Alternator+Mount £176.25
Starter £59.7
Flywheel £105.75
Clutch £43.19
Timing belt £54.94
Water pump £14.74
Spigot Bearing £9.98
This all comes to about £1000. On top of this was the fuel injection system and the ECU. I used a Megasquirt and Jenvey throttle bodys but there are plenty of other options such as bike TBs which can keep costs down.
Out of interest what would it cost to build a 170 HP Pinto?
For those interested there are plenty of pictures of the engine change here:
http://www.pbase.com/brycheiniog/fury
And pictures of the spainish tour here:
http://www.pbase.com/brycheiniog/se7ens_tour_spain_france&page=all
Jonathan