Fallowing the thread I added above will allow the safety switches to remain actives with no major wiring changes.
Looking at the battery 103990 switch next to the magneto switch 103991 I decided to see what would happen if a 103991 (Magneto) switch was placed in a Battery Ignition tractor. With the exception of a frustrated person wondering why nothin works the outcome would be rather harmless.
In the OFF position the R and A terminals would be connected Ground, no big deal.
In the RUN position the I, A and R terminals would be connected, nothing would happen but no harm would come of it.
In the START position the S an I terminals would be connected, once again nothing would happen but no harm would come of it.
On the other hand, if this situation were turned around and the 103990 (Battery Ignition) switch were placed in a Magneto tractor things get a bit more interesting and a whole lot more expensive.
In the OFF position none of the terminals are connected and all is well.
In the RUN position the B, R, A and M terminals are connected and magic smoke will be released from the Magneto.
In the START position the B, A, S and M terminals will be connected and the engine will turn over but there will be no spark because the magneto already is toast.