iv seen speedo face plates/stickers that are multi fit that are marked with both mph and kph
you will need to pull the speedo apart and its been a while since ive seen them but thats the easyest way.
otherwise i have a local company in sydney australia that can totaly rebuild it to read mph only using the original face plate im sure there is more than one company in the world that do this so there maybe someone closer to you
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