I can't really help as I've not done this, not properly anyway, but obviously you will need the right measuring equipment for measuring an internal diameter, I reckon the micrometer will have to be accurate to 0001" eg a tenth of a thou. Unless you have that I think you will need the machinest to do this for you.
You may be able to make a rough measurement with a vernier, that will tell you if your rods are oval at least.
What you are looking for is generally ovality in the rod I.d. Which obviously started life round. The top and bottom of the rods sometimes get beaten out of shape by the forces of compression/firing, a machinest can fix this by taken a little metal off the joining face of the rod and then machining the id round again, due to the accuracy required this machining of the I.d. may be done by a special honing machine. This fix only works if the id when measured at the side of the rods is correct eg not worn or out of shape as no metal is removed from the sides when making the rod round again.
Rather than spend money on getting this sort of work done on my oem rods I simply bought new rods from thunder engineering, it did not cost much more!
