73 kframe on 72 abody

Take a look at the mounting bolts.I dont know about your bolts, but mine IIRC had a special ramped area that helped to center the K to the frame.Grinding out the K will not allow the ramps to do their job. Moving the frame rails will. But that begs the question, Whats going on here?
The FSM shows in detail how to check the frame alignment using nothing more than a flat floor, a level, plumb-bob,and a sharpie.