if there is a minor issue with ur engine, get it repaired
if a complete overhaul is needed........ get it swapped with the same kabuli engine, they are far better
an overhaul would be expensive as well
i would emphasize here specially on a swap with some VTEC or any other honda engine
city's arent meant for it and its suspension and brakes are already at par with the IDSI...
you will disturb its weight, balance and the gearbox would also not match.......