I run McCoy MC59 or Enya #3 plugs in most of my engines which are both hotter than the plugs you listed with fuels ranging from 5% nitro up to 30% nitro and dont have issues with preignition or detonation. Car engines running at 35,000rpm or 4-strokes running at 12,500rpm don't matter. Just need to remember "Lean is Mean". If the engine is over compressed with higher nitro, you will need cooler plugs and/or less nitro. The cheapie engines tend to be under compressed so more nitro is tolerated. Truly though, the only way to determine what plug the engine needs is to try several plugs and using a tach take note of the results. The tach will tell you which plug works best.

And for the record, idle bar plugs aren't intended for Schnuerle ported engines. They are designed for use in cross flow ported engines.