Each pin was installed in the flywheels (without the rods) to check the female rod endplay at the thrust plates with a divider. You measure your rod width, and subtract it. The pin(1.2495) I want to use has the best endplay for these parts at .023 - I'll use this pin.
The ORANGE paper has the calculations for honing the rod races to proper bearing fitment. My rod race diameters need to be 1.6255. Sometimes depending how they "feel" on the slip-fit test, I might make the center rod have only .0008 clearance to tighten it up a bit.