Hi
You will need to pull the flywheel to get at the ignition. Inside you will find a coil, condenser, and a set of points. Plug should be a modern equivalent to a Champion J-15 and gap set at .027. Points should be cleaned and set at .018. Condenser could possibly be obtained from Doug Penn who is a member of the club and is in the directory and on the site. Probably need a new spark wire lead. This can be obtained via the club listings or by contacting Brillman Company. Gearcase lube should be Lubriplate 105 or John Deere Corn Head Grease. Pump used a brass plunger vs. an impeller. Make sure it is pushing water out the pee hole at the bottom corner of the exhaust housing. There are several suppliers for Decals. I like Decals from Dixie Hammock for the champs but others are available. Carb should be a Tillotson MS-85C. Simple carb that will probably need to have the cork float resealed. As far as adjustments go I would contact Harry Nicholson who is a club member (in the directory) and purchase a copy of his Champion Pre-War Guide 2015. This has all the info you need regarding the carbs adjustments plus a whole bunch more re fuel mix,models, parts, etc. Very inexpensive if he has any copies left.
Hope this helps,
Kevin