70 up charging system upgrade question

Well I haven't done this with a ignition like yours. But I have with my msd setup. Basically the same,interrupt power to the coil to create a spark. Result is a spark you can see and hear. From the coil wire to ground. Only hearing it from under the distributor,that's not right at all. Try it again with the coil wire close to ground away from the distributor. Distributor has nothing to do with this test. You are testing the ecu and the coil.