Any good automotive machine shop can advise once the engine is apart. The pistons I use for rebuilds are US made copies of the KS or Mahle German ones, and work well. The short blocks that Volvo sells are all rebuilt in North America by the same sort of shops you can contract with anyways. Be sure to check the rod small end bushings - it is best to replace them as a matter of course and keep the pin fit to the minimum spec as the turbo motors have a tendency to pound them out oval in service.