I am curious, have you tried an ignition coil yet? You may want to have the coils available voltage output checked. This is, maybe was, one of the tests that most technicians performed on an engine that was connected to a diagnostic scope. A technician would remove one spark plug wire and monitor the voltage increase to that cylinder, this is more commonly known as spark demand. The maximum output reflected the coils ability to generate sufficient spark. Local auto stores sell a low budget device with a thumb screw that is somewhat self explanatory, in the back ground is a scale that reflects the voltage output. You simply adjust the screw to either increase or decrease the gap between two points. When the ignition coil discharges the voltage will bridge the gap on the tool, the further the spark jumps the stronger the coils output. I believe your ignition coil should have a total reserve of 40K+. You may or may not be capable of getting that high of a reading with this hand held tool so anything >25K demonstrates that the ignition coil has the potential to operate.