Going back to your very first post, you say "... battery style ignition". The conversion magneto pictured is a small completion type for this engine that is for ignition only. There just isn't any way a #10 lighting coil can be added to this magneto.
The magneto used on the '55 and later Hummers, Ranger, etc. is maybe 25% larger in physical size and has a #10 lighting coil. The timing side engine case and cover was changed accordingly.
As I read through this thread, adding a lighting coil just can't be done. Only way out I see if you wish to use this magneto for ignition is to use a rechargeable 12V LI battery along with LED lighting on a constant loss basis.
Log on Thumper Talk and do a search on Total Loss Lighting. There was a post by RockerYZWR dated 12/31/16 that gives all the details.