What CNC-Dude said!! It takes a really competent machine shop to perform a proper align bore, or "line bore" as we call it. Most shops just grind the main caps and then bore the crank bearing surfaces to a new center line. A true align bore is done by boring along the correct original center line spec. There are VERY FEW machine shops equipped to do this or even willing to do it correctly, and many blocks are too damaged to repair in this fashion!!
One of the shops that I used back in the late seventies and through the eighties in Nashville has long since closed. The old machinist is still around. He particularly hated to see me bring him a Chevy six because of the problem mentioned above.
I don't know ANYONE around here that does it correctly anymore!! We also used to bore the cam galley so we could use camshafts with much larger lobes. Not sure if anyone does this anymore either!!
