This is a test –
I don’t think the 15 came with an electric starter. The 18 did. It may require some fancy engineering to fit the 18 flywheel & starter to fit.
You would need the starter bracket and starter. The bigger flywheel with the ring gear. A carburetor bowl with a 12 volt choke solenoid.
Later models mounted the starter solenoid under the motor cover. Then there is the wiring …
