Identifying a Kohler engine that's missing the tag on the side
 

The CC 125 that I have has a Kohler K301a in it. The 147 that I have posted here has, if I remember correctly, a K321A. Then there are two more Kohler engines that my grandfather had laying around - one, if I recall correctly, is a K301A, but another, that he had apart (looks like rod bearing failure), doesn't have the same identification plate on it that all the other engines have. Is there something else I can look for, such as maybe a stamping, that would help identify what the engine is/was?

Measure the bore size. No better way than that.

What he said. Download the service manual and it will list the standard bore size for all the k series engines.