GM actually has .0006"(6 Tenths) as being the low side tolerance and up to .0036" as the high for bearing clearance on the 194,230,250 and 292 engines, so anywhere in between this GM calls acceptable. Stock GM cranks out of the box aren't even round within a .0001" most of the time. I have seen some as much as a half a thousandths out of round right out of the box.
Keep in mind that GM doesn't make any parts themselves, they have outside manufacturers all over the world make every single nut and bolt and engine component for them, they just assemble them in Detroit or other assembly plants around the country. So it just depends on who made the batch of cranks or machined the blocks during that assembly period as to how precise they came out.
