Hmmmm...so ya say ya want it in "kilometers" instead, huh Calle?!
Does it matter what color..err, I mean coloUr it comes in???
(...couldn't resist the joke)

And btw, I don't see why the non-American market standard Bonnie speedo in KPH wouldn't work, as I'd guess the cable hookup and the ratio would be the same on both the large BA/Speedy speedos and the smaller standard Bonnie's...though this is just a guess.
I'd say maybe contact your local Triumph Dealer and the Parts(Spares) Dept manager might be able to give you a definitive answer to this.