Jim, the ballast resistor [actual name] started with the change to 12V and continued to sometime in the 60's when the switch to an internally resisted coil happened - the purpose of it is to limit the current thru the coil to prevent it overheating - as said somewhere above, the ignition circuit is setup so the resistor is bypassed while cranking in order to insure a strong spark when the starter is drawing a lot .... the primary purpose of the resistor in the circuit when running is to prevent overheating of the coil and it's eventual breakdown .... so you can eliminate the resistor by using a later style internally resisted coil, but the resistors work fine and are dependable - most coils will be labeled as needing an external resistor or not needing one, do not use both
thinking of that reminds me that the purpose of the condenser [capacitor] is to limit the amount of arcing at the breaker points when they open to 'break' the primary circuit in the coil, which induces the high voltage secondary circuit to send a jolt to the spark plug .... any time you replace the points, replace the condenser as well
and by "original style foot starter-type ignition switch" you mean the mechanical contact box on the starter? AFAIK they're not available anywhere, but they can sometimes be repaired
Bill
