We've found our new project!  It's a 2001 Fiesta Zetec S with the revised 1.6 Zetec SE engine which is stronger and puts out a bit more power than the earlier engine.  Sadly it's an insurance write off after having a small prang with it's last owner but that made it cheap enough to buy.  It only really needs a new bumper, a couple of headlights, and a radiator in addition to the race preparation.