If you have swapped the gauges the wiring might not be the same even if the main wiring connector fits. Might need someone with more knowledge than me for this.
In some Japanese cars the dash lights wont work if the tail lights are not functioning, not sure with a Datto though. Check they ALL work first then trouble shoot.
Fuel gauge issue is normally fixed by cleaning the contacts on the sender unit with fine sand paper etc, as long as the wiring is ok (and the float is still sealed) that should do the trick. When all else fails double check and clean all earth wires, maybe add some more.
I don't know if I should be flattered or insulted Mik Anyway, here are a couple of pics. Rims are dusty and dirty but could still use a polish, tire tread is 40-60%. Pics are of two wheels only but I have 4 all in similar condition. Cheers, Levey.