This measuring of overall axle lengths to determine correct axle swaps is tricky.
While generally having the same tapers, different axles and cranks have different widths across the flats. So, for example, a Sronglight crank rides too far up a Campy axle.
Sutherland's has this all worked out with their "axle end factors".
Joe Bender-Zanoni
Great Notch, NJ