First, check for 6 volts between the negative terminal of the coil and ground while the engine is cranking. If you get 12 volts, the points are not conducting when closed, if you get 0 volts, you are not getting any voltage to the coil or the points are not opening. As for the 12 volt spark, no, if everything was right, you would get about a 250 volt spark.
When you have current flowing through the coil, a magnetic field builds up around the coil. When you open the points, you disrupt the source of the current, so the fields collapse and generate a flow of current. Many people mistakenly believe that the voltage goes up because of the turns ratio between the primary windings and the secondary windings in the coil, but that is not true. The magnetic fields are developed by current in the primary windings, but when the field collapses, it generates voltage across both the primary and secondary windings of the coil. But the ratio is only 100:1 so that would only generate 1200 volts in the secondary.
The complete formula for the step up in voltage includes time difference. In a normal AC transformer, the ∆T (delta T) nulls out so only the ratio and applied voltage determine the secondary voltage, but the ∆T is different in the charge time and discharge time of a coil of a Kittering ignition system. The coils in the old Kittering systems were actually a tapped coil, so the full voltage was felt at the spark plug, but the tap, acting like a voltage divider only sends 1/100th of that voltage across the points, or somewhere between 160 and 250 volts depending on RPM.
Modern ignition systems work differently so the coils are actually wound as an Auto-transformer. That keeps the high voltage out of the computer that is triggering the spark. We just keep calling them coils though.