There is absolutely no doubt that the can is genuine Stewart Warner and not a repop, the big question lies in the face. I'm going to stick with my original guess for several reasons. I have 2 working unmolested 1947 speedos and everything you stated about them is true, but I have never seen an actual 1947 export unit in Kilometers so my guess is still a guess.
1. The crimp on the bezel of Keith's speedo looks perfect, I don't think it has ever been opened. If the can was opened then whoever put it back together must have used a lathe to roll crimp the bezel back onto it.
2. If you look closely at Keith's first picture you can see the window for the dash light, the "0" in the photo date on the picture is in the left end of it.
3. All of the 41-46 speedos had a bulls eye, civilian and military, this one has a plain circle in the center. As Scoot mentioned, the 47 faces were silver plated and the center circle had a fading shadow printed on it using a decreasing density dot pattern, Keith's does not but that is just part of the confusion.
Another puzzle is the number style which does not match either the 41-46 style or the 1947 mph style which used block shaped numbers.
Perry Ruiter would probably know, I stole this from his web site...http://www.ruiter.ca/mc/info/SWSpeedoDating.html
look at his comment about the kilometer faces for 1947
I'm not trying to stir anything up here, I would like to know what it really is myself.