Hello,
This is true, the glow engine you are copying uses a glow plug with a thin wire element in it that glows, For your spark plug to work it will have to fire continually, or at the right moment. I suppose you could put a "cam" or a bead of weld somewhere on the flywheel that triggers a microswitch at the right place wich grounds a coil to fire the spark.
Anyways that looks like a fun project, wish i had the time
Bry