So I've looked at that bike on Google, and I've looked at the Scott bars on Google, and in none of the dozens of pictures of various set ups with Scott bars do I see a stem in use that I would call an MTB stem. What exactly are you in search of? MTB stems "usually" have a 25.4mm bar clamp diameter, and are also 25.4mm in diam at the insertion into the headset. They also usually angle upward from the headset at around 30*. Road stems of the same era had a 26mm (usually) clamp diam. and were 22.2mm in diam at the insertion into the headset. They usually had zero rise to the horizontal portion and often had an appreciable amount of negative angle to the horizontal portion. Any stem with the proper diameters to fit your headset and the handlebars will work. Modern stems are mostly "threadless" and not compatible with the "quill" stem your Centurion needs but quill stems are still made and can be obtained new, but any bike co-op will have a large carton box full of legacy quill stems in all kinds of shapes and styles. FWIW.