79 Triumph still not sparking?

A coil is a "choke" electrically speaking. Meaning that dc current should not be flowing to the spark plugs except when the primary field collapses. So if you are reading twelve volts at the spark plug there is something wrong. There should be no direct electrical current getting to the plugs. If there is then the primary coil is shorting to the secondary coil. So try a different coil.