I need help chosing plugs for my new motor. I have AFR heads so they need to have the washer/ gasket on them. The motor is a 383 with 10.8 compression and will use N2O every once and a while. AFR says to use AC FR3LS and move up from there if they are too cold of a plug. I don't want to keep buying plugs just guessing on the heat range. any ideas?