I take it the 0v + to - was without the ignition on? However the 12v and 0v on the coil terminals indicates that something is wrong as a ballasted system should normally only supply ~6v. The only time a ballasted system will supply 12v to the coil is when the starter motor is turning the engine over. So the possibilities are:
coil open-circuit (but its 3.5ohmn resistance says no),
ballast resistor has been removed or bypassed,
contacts on starter motor are permanently closed even when not starting which effectively bypasses the ballast.
The fact that you have found a non ballast system coil installed indicates to me that someone has fiddled with this before either as a bodge or intentionally.....