The stock TB for the Contour Zetec was 55 mm. The critical dimension you want to measure is the throttle plate diameter. The Zetec in the ZX2 and the Contour use similar intake manifolds. The Gude 58 mm TB for the ZX2 Zetec should bolt right on with some minor grinding needed to port matech the TB to the manifold.
The image below shows a modified 1996 'Tour 55 mm TB which was bored and polished to take a 57.6 mm throttle plate. Air flow measured on a flow bench was ~18% higher than stock at equivalent pressure drop. I have this one mounted on a 2000 ZX2 S/R.
57.6 mm Zetec throttle body
