This is obvious Mark: remember, the chondas are made in the same three types as the Hondas: GXV120, GXV140, and GXV160. Quite a lot of parts are different between those three engine sizes. As Rob and Theo said, provided both of your chondas are GXV140 clones, your only problem will be checking whether the manufacturer deviated from the Honda design in some minor way, right where it will be least convenient. I suggest you check that the parts will bolt together before you get too far into the project. If the two engines are different sizes, there will be more subtle differences (different flywheels, different ignition modules, different ignition module mountings, spacers under ignition modules, etc.)
Rob and Theo both know way more about these differences than I do, so I'm sure you'll be able to get good information if any difficulties crop up.
