As for 351 not starting, oscilloscope will solve that in 5-minutes. Check ignition-pickups at stator for proper signal:
Adjust pickup-coil closer to triggers to increase voltage. Then verify that same signal arrives
at the CDI box as well with full-strength. A lot of times, the connector or wiring in between is bad.
Another common problem is wires are reversed. Waveform looks the same, but starts on negative slope instead of positive. This throws off CDI and it won't fire.