One other comment on this subject:
In original literature from another GM manufacturer, occasionally an engine block might have a defect that would prevent using standard parts. These engines would be assembled with slightly oversize bore, or slightly undersize bearings, or both. A mark would be made in the engine number, and the vehicle would be sold to the original purchaser at a discount (often, to fleet sales, such as taxis). I do NOT have sufficient GMC literature to know if GMC also utilized this practice.
While historically interesting, it becomes a moot point at the machine shop. What is important at the machine shop would be if the block and crank would clean at clearances acceptable to published standards, and pistons, rings, and bearings would be available.
Using the dimensions from the "A" build would be like reading the numbers on the jets in a carburetor and expecting to know the size. This is why measuring tools are made.
Jon.
