If my memory is still good those were made by Scott/Atwater who also made firestone motors. Im thinking try ebay and see if you can find one for a firestone or early scott/atwater.
I believe that has a Bendix-Scintilla magneto with a rotating magnet in the center, am I right? A similar mag was used on some old Mercurys. Jim Judkins has new reproduction coils available. oldoutboardjim@hotmail.com
Champion is a stand alone brand.
They also made a little motor called the Champion Hot Rod They ran in a class with the Thundering Mercs.
All you heard was a little buzzing noise as they went by.
