Re: 1960 Johnson 40hp starter&gen
Generators were sold as an accessory kit, consisting of the generator and mounting bracket, the belt, regulator and ammeter. They are a little hard to find, certainly complete, and you may not want to bother with set up and assembly anyway -- may suffice just to use a shore charger periodically. If you are into restoring motors, you can probably put together the system as you will already have some sources.