The Zetec is a great engine but in N/A form would be a bit low on power for what I imagine is a heavy car. It's also a bit expensive to covert to RWD and get lost in that engine bay.

A modern 5.0 Ford Mustang crate engine would be perfect if a bit on the pricey side...

http://www.fordracingparts.com/crateengine/main.asp#mod