you can reset them mate once they are fitted to the car, doesnt take to long to do
it might be handier to get a dodgy garage man to reset it for you as it kinda hard to explain and times the figures could end up not in line and people would get suspicious if you were to sell the car
I believe you can remove the mileage part of the cluster and swap it with your own if your careful as im sure itll be fiddly
can you put a ek9 clock on a ej9 and would everything work fine ?