That looks like the engine serial number. What I am looking for will be in the format of xxxxxx xxxx-xx and then next to it will be 18030658 . The numbers I am looking for will be stamped in to the valve cover, or could be stamped into the side of the block. or there are a couple of other locations, but they will be stamped numbers.
I suspect that the new engine is set up for push mower type applications which have an aluminum lightweight flywheel. Whereas the engine that you need and what was probably on your splitter was the heavy cast iron flywheel. Some of those engines can be switched to the heavy flywheel easily without having to replace the entire engine.