Any 5 cylinder engine that came in those cars from the factory should work. However, if your car is naturally aspirated, you should probably stay N/A. Ask anyone, and they will tell you it's more work than it's worth to convert to the turbocharged 5 cylinder from 2.4T, 2.5T or T5 models.
If you're asking as far as performance, you may want to ask around on a Volvo forum such as Matthew's Volvo Site or Volvospeed. You'll get more help there. I'm not aware of any swaps in an S60.
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