It sounds like bore size is not consistent , and varies from top to bottom or in the middle..is that what you mean ?
Bore off center , you would have to dial in onooe bore , then go to next and dial in , while measuring the distance in between , that would be off center. ..if the centers were off spec..if you even know the bore center spec.
If your bore is not same size top to bottom , it will never live very long.. hard on parts..