Here in the northern ireland the stupid annual mot rules state that the speedometer must show both kmh and mph. NI road speeds are in mph and Ireland is in kmh.
I've had to fit G35 clusters to 2 v35s. Both worked fine, the only differences are that you lose the sidelight warning lamp and the cluster backlight doesn't dim with the clock display. G35s have a manual dimmer for dash lighting.
I'm sure there's a work round on the backlight somewhere but it hasn't annoyed me in 6 years