I bought a JDM unit off of eBay first but the scaling was crap. Seems like you are going way too fast all the time. Then I bought an Israeli speedometer and it was much better. My big thing is the odometer be in KM as well.
Now here is the big issue, for some reason neither the jdm unit or the metric speedometer allows the interior lights to work. I can swap back to the usdm unit and all the lights around the HVAC work again but the other two clusters don't allow them to come on. It's very strange, all the the cluster lights works, interior illumination just not around the radio or HVAC