does nobody make new speedo dial decals
just swap to a MPH scale
i.e leave the pointer and gears alone and alter the scale.
at one point in the UK you could get MPH decals and KPH decals to allow compliance with standards when using a car you imported or taking a car to a KPH country
Australian valiants also went through a MPH to KPH change and you could get new speedo face decals to assist with the swap...
nobody messed with gears or gauge calibration. Just stuck the decal on and pretended that km were miles for the odometer