almost all the bikes outside the US are in KM.
depends on the import rules for motorcycles in your state.
For example, I imported a US market harley into Canada. Since it was a US bike, it was in miles and not able to change the display (some newer models have that option). Import to Canada did not require to change the instruments, but I bought a ordered a new KM speedo from the dealer I purchased the bike from in the US (part was cheaper in the US than Canada).
So it depends on what is required for import, but you can also easily purchase a new speedo in miles. Depending on the model, HD may offer a few selection of speedos for a specific bike, some with more features.