Those older Briggs are fantastic engines.. Here are some things to clear up some questions.
1. There is no primer or choke, The engine has a Self Choking "Choke-a-Matic" Carburetor which automatically chokes the engine on cold starts.
2. The little knob does not shut the spark off.. It simply closes the butterfly valve in the Carburetor restricting the air flow so much the engine stops.. That's the theory anyway..
Kori
