The grease is the usual way to catch stuff like that in machining.. but I think it would be best to also pull the injectors and vacuum from the top... since turning the engine over might suck that stuff into the precombustion chamber holes depending on the starting position of the piston at the time this event happens.
In some instances the reamer will produce metal filings... since it is used to realign the glow plug/precombustion chamber hole... have forgotten which set of conditions produces this... but I read it in the FSM...