Your price is too high for the used piston, some more without the rings. with this price better people buy a new set come with rings for rm 7++. rm300 - rm400 is ok for used set
Would like to ask what are the values you are using on the alignment of your car? Currently i am running slight all toe in all 4 wheels around (tuned by the tire guy), camber and castor untouched at all...