i've got a kph gauge cluster, but i'd really like to put on some reverse indiglos i got. they won't match up unless i have a MPH speedo, would it be possible to re-calibrate the speedometer w/ the overlays? or would i have to get an entire new cluster, and is that even possible?

could i just trade w/ someone or sell these and buy a new one? i'm not sure mainly because of the strict CA laws regarding the odometer, of course i would make sure they matched up but even so, i'm wondering if it's something i would be able to do or if i should just give it up and stick with the stock gauges.