It’s not the journal size it’s a factory machining alignment issue. And you don’t use a bearing scraper or knife to do the job either. And it’s thousandth in measure.
Have you measure the cam journals prior to assembly? If so, what did you use. The alignment issues people speak of, in my experience, is a distorted bearing due to a tight journal. Lastly, the bores I find to be undersized are so by a half a thou to 1.5 thou (.0005-.0015).
Disclaimer : If you aren't measuring with a .0001 resolution dial bore gauge set up with an anvil mic we will probably have different experiences.