CID = (Bore + Overbore)*(Bore + Overbore)*Stroke*cylinders*0.7854

Stock -
CID = (3.562+0)*(3.562+0)*3.94*6*0.7854 = 235.6

0.030 overbore -
CID = (3.562+0.030)*(3.562+0.030)*3.94*6*0.7854 = 239.6

0.060 overbore -
CID = (3.562+0.060)*(3.562+0.060)*3.94*6*0.7854 = 243.6


regards,
Leon