The "secret" issue with trying to measure these engines' bearings/journals is: the journals don't all wear evenly across their whole widths. Most often I have found that the center main bearing is evenly worn, but it is the only one: the outer 2 are usually wider toward their outer ends, and the #2 and #4 bearings vary, sometimes being wider at one side and sometimes being straight all across. This is shown using Plastigage, if when I find one that is 'worse than usual' I will Plastigage it twice to be sure, then go from there with the measurements it shows. I have done them 3 times on occasion, too. It is almost always the #2 and #4 mains that do this, and once in a while the #5 (by the points) is often the worst (loosest) wear. That probably makes sense from the standpoint that the main journal fills from the center via the oil filter. The rods, though, are more often evenly worn across their faces, which is interesting given they get less oil than the mains.
Plastigaging my old Ford 200 CID inline Six (in 1996) when I rebuilt it was a similar experience, although there were no stamped numbers on that one's crank nor rods: it was just measure it, guess which bearing thickness might work, Plastigage the results (and then buy new bearings again, or trade them, if it was too loose). During that one I became much more practiced at using the ID bore gage.
