When New Cylinder Block is Used:

WARNING: This page is about a different car, the 2003 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.

Check the cylinder bore grade on rear left side of cylinder block, and select a piston of the same grade.
If there is a corrected stamp mark on the cylinder block, use it as a correct reference.

Fig 1: View Of Identification Stamp
Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: Locating Identification Code
Courtesy of NISSAN MOTOR CO., U.S.A.