A good dial bore is accurate to .0001 of an inch or better (if you use it right). Anything else, not so much. I had a machine shop tell me, after I told them what I wanted the intake side of my heads milled, that he would mill them the same as he did Chevy heads, cause Chevy was racing long before Chrysler. I told him he was wrong on both counts, and found a different machine shop. Funny what you remember...