Unless the thermostat is not working correctly, it should not be possible for a radiator to 'over cool' the engine.

The only problem a too-large radiator could create is that maintaining a proper temp inside the engine could result in very little flow through the radiator. Less coolant flow through the system could lead to small hotspots within the engine block because the coolant is flowing slower. That's why big trucks here in the States use covers over the radiators in the winter, so the coolant still flows at a good clip through the radiator. On a Volvo this might not be such a problem because when the thermostat is closed it also opens a bypass and the pump circulates coolant around the block, not just against the closed thermostat.

Running an engine somewhat cool is not a problem. But running it VERY cold for a long time is not good. The combustion process forms several corrosive gasses that normally just blow out the tailpipe, but if the cylinder walls are cool enough they can condense in the combustion chamber and cause corrosion. Not exactly a dramatic difference in wear. The engine will also carbon up more easily.