Actually, I would LOVE to have a metric speedometer, since we are S.I. (System International) in Canada. I have seen them come up on German ebay a few times, but I don't speak German. Now, if you wanted to swap a Metric speedo for an Imperial one, I'd be there for you.
All you need is to purchase the kilometer insert. Look at Lenk Tuning website, they sell a set of white gauge inserts and the one for the speedometer is kilometers. You can order Lenk items from the Source .