Jeff, you are doing exactly what I did. Spark gap, colder plugs (7s and 8s myself as well), increasing coil dwell, etc. I still get the occassional misfire, but that could be attributed to my fueling. I don't know. Now that I have meth injection, I will lean out my map a little more and see if that helps.
Maybe timing? But that would show up in AFRs.