I bought some gauges:
I tried using them to measure the cylinder diameters today, and wasn't very impressed. The details are pretty much all in the attached PDF.
First I set up the bore gauge to 2.98 inches. Then I measured it with some calipers and got 2.9977 inches.... So they immediately disagree by more than the service limit in the manual. Nice.
I measured all of the bores and recorded the results on that first page. Then I ran a quick test with the very first bore measurement (0.0437): 2.98 - 0.0437 = 2.9363, which is smaller than the stock size of the cylinder.... Or 2.9977 - 0.0437 = 2.9540, which sounds more right.
So I calculated out all of the diameters using 2.9977 as the base length of the bore gauge. One reading was over the service limit, and one taper. Since I'm not going to put money into the car to do anything about that, I'll just keep swimming.