Block out of square

I'd say the block was positioned wrong when they went to machine the main bore. As the first phase of the rebuild. Then the rest of the work that's indexed off the crank centerline (and the front of the block) was done off that screw up. You could fix the block simply enough. Or cut the bell simply enough. Or tell them they need to fix it. I'd tell them they need to get you another engine, or another block and transfer the parts.