piston broke, need assessment

[jmshepard]

My 220,000+ ( many racetrack) mile 1980 SC motor is undergoing a rebuild by a professional shop. During the removal of the #5 cylinder, a piece of the piston fell on the floor. A piece of the land between the oil rings had broken off. If you were to look at the top of the piston as if it was a clock face, the broken section would be from the 12 o'clock to the 2 o'clock positions. The piston did not damage the cylinder wall. When it broke cannot be determined, could have been 100,000 miles ago, or when the mechanic pulled the cylinder off and the piston went through a section of unused cylinder wall. The engine had never given me any problems, I decided to get it rebuilt as a preventive measure. The rest of the engine is in excellent condition.
Here is the question, does this broken piston represent the only piece of the engine that will fail or is it the harbinger of more failures to come? The shop found a used piston in great shape to replace the bad one. The mechanic suggested a new set but I requested the engine to be reassembled with the old set. Have I made a mistake?

Also, kudos to camgrinder on the quick turn around on my cams.
thanks John!

[john walker's workshop]

they occasionally break out a section of ring land. not too unusual for a high miler. reusing pistons and cylinders is always a gamble. new ones would be a sure thing that the rings will seat, used ones, a maybe, probably, most likely, if they look and measure out ok. i don't warranty the performance of used P+Cs. i figure the customer has been informed of the potential issues and it's the customer's choice to do what he sees fit after that, usually because it's a cost issue.