Re: OP's bore diameter information

From posts #1 & 30 this may be derived:
If the piston-to-wall clearance was correct (.0005"-.0015") at a bore of 90.920-90.925mm, then with a actual measured bore of 91.008mm, clearance would be nearly .0048", or more than triple the high side of correct.

The observed wear pattern is consistent with this large clearance; thrust is concentrated in a small area.