I counsel all to think carefully before flogging any NIB engine in their collection for a wad of cash.

Sure, you'll make some money (which will probably end up being spent on more modelling goodies fairly quickly), but chances are that if your engine was anything nice or special you will eventually live to regret selling it.

Far better to hang on to it, run it, stick it in a plane and fly it. The satisfaction gained by doing that far outweighs any transient financial gain, and the engine will get to do what it was built for rather than sitting around in a dusty display case.