Buck,
The case is the same as mine, but from what I can see of the cylinder it is round rather then square. Mine has a single pinned unpinned ring and stamped aluminum rod. Kioritz just increaes the cylinder bore size to create the different displacements from 21 to 25. The port timing on mine is very conservative. Intake=55 degrees BTDC,Exhust=60 degrees BBDC,Transfer=45 degrees BBDC. Yours ought be a great gasser for small planes.

Dave