My Dart wont start and i think i may have blown the msd, about a year ago i moved the ignition into the car and wired it to a cut off switch on the dash, anyway after changing the motor and altering a few things i stupidly put the large black earth to the power with the red by mistake and there was a pop from under the dash when i put power to it.
How can i test it.
There is 12v on the switch source with the key in the on position but there is no voltage at the coil positive with the key in the on or crank position.

9. How can I test an MSD ignition to see if it is working?
Checking for spark output of your MSD is easy. Following is a simple procedure for testing your MSD for spark.
1. Turn the ignition switch “OFF”.
2. Remove the coil wire from the distributor cap and place it 1/2” from ground. DO NOT CRANK OVER THE ENGINE. When you continue with this test, a high voltage spark will jump this 1/2” gap so make sure there is no fuel or flammable mixtures near the plug wire end.
3. If triggering with the Magnetic Pickup (Green and Violet):
A. Disconnect the magnetic trigger wires from the MSD. Turn the Ignition Switch “On”. DO NOT CRANK OVER THE ENGINE.
B. Use a paper clip or jumper wire to short the Green and Violet wires going to the MSD together several times. A spark should jump the gap every time the wires are shorted.
4. If triggering with the White wire (points/amplifier):
A. Disconnect the White wire of the MSD from the distributor trigger or ignition amplifier. Turn the Ignition Switch “On”. DO NOT CRANK OVER THE ENGINE.
B. Tap the White MSD wire to ground several times. A spark should jump the gap as you do this.
5. If there is no spark, substitute another ignition coil and repeat the test. If there is now spark, the coil is at fault. If there is still no spark it is possible that the MSD Ignition needs to be serviced. If the warranty period is over, MSD offers repairs at nominal fees. For more information on repair services, contact our Customer Support Department at (915) 855-7123 or msdtech@msdignition.com

http://www.msdignition.com/uploadedFiles/MSDIgnitioncom/Support/frm29233_tb_top_ten.pdf