"That rod was electroplated with copper from the factory, it was a fast easy way to adjust for machining imperfections"
Odd, that ISN'T what copper plating is for a full circle rod for a two stroke that does not have a split big end. The full circle rods use a roller bearing on both ends, big and small journals, and, they use the rod material, specially heat treated to bearing race hardness so they will work with those roller bearings.
To harden the rod all way to bearing race hardness, WILL cause the rod beam to become so brittle, it will fracture very easily. Since the heat rreating process can only be done for one type heat treat level, there has to be a way to change the hardness, to a softer hardness in the rod beam. Copper plating does this, by drawing heat away from areas it is applied to. Virtually, the rod gets heat treated with two different conditions, bearing race hardness for the bearing races, softer in the bog and small end outer metal and rod beam.
Also, consider that copper ISN'T a hard metal, is a lot softer than the steel the rod is made from, and once the rod bearing and pin bores, and big end parting lines are done, there is NO copper left on the machined areas of the steel. Shoots the heck out of the theory that the copper was added to "build a rod up for re-machining" after it has been machined too small, doesn't sound like it cuts the mustard.
Now, in Model T and A rods, there were poured bearings used, copper base, then lead indium for the "pour insert", but, not only copper, and it stayed on the steel as the bed of the bearing material against the cast iron or steel the rod was made of.
Ever see a rod that had copper as a bedding material that was machined UNDER a bearing insert, to build it up to support the bearing? I haven't either, only in the Model T and A poured bearings.
Copper has more to do with heat treating of a connecting rod, than building it up for machining. I would think a partially copper plated rod would be one that failed heat treat on one end, or other areas, and was plated, and retreated to get it to production status, instead of failed and/or destroyed.
I have seen Ford Le Mans FE rods that were completely copper plated, save for the machined areas, done for heat treat differences in the bearing/pin bores during manufacture, nothing else.