You have to be careful how you measure a worn rod to get the correct centre to centre distance because of the way they wear. The small end wears downwards and the big end wears upwards so you have oval holes top and bottom. The only way is to measure the distance from the top of the small end to the bottom of the big end (the unworn sections) then subtract half the diameters of both the wristpin and crankpin (and maybe another 1 or 2 thou if you want to get anal about it ).

The rod in my Rossi 45 had worn .012" on the (unbushed!) small end which had the same affect as raising the liner by .012" (altering the timing) and also lowering the compression. Making and fitting a bush was fun but very time consuming.