Yes, Laynard would kill spark for sure. Thats on OIS ignition, Not too familiar-others can chime in.
But Fuel/Spark/Compression.....You can check fuel delivery, check spark on each with a tester or a helper, and always good to get compresson readings.
Every one of those motors I've worked on have warped bowls. Wouldnt explain it totally not starting, but would idle/run crapy-Just mentioning.
see what others say about the Optical iginition and checking it. Good luck.