NGK Plug recomendation

Edelbrock Perf RPM head requires a 14mm x 3/4" reach plug. XR4 & 5 are short reach plugs. 4 is hotter than 5. 10.5 compression with 600 hp should probably be in a 5 or 6 heat range depending on fuel type and quality. Maybe colder yet? Some NGK numbers to look at would be FR, or GR series, R5671A-_, or R5672A-_ series. 5/8" hex would be recommended for headers. Not all of the race series plugs are available in -6 heat range. What plugs were used to dyno at 602hp? May want to follow with the same.