Stop reading this stuff. you will go blind.
BS************BS All you will achieve is makeing yourself poor
and shorten the service life of the distributor using wide gaps.
set the plug gap at .035" for a HEI distributor.
The slightly cooler R42T RV8C will burn slightly darker cooler.
Do not read anything into this. It don;t mean squat.
The plug is the right heat range for performance driving using that head on a 350.
More detonation threashold.
Its is the "stock .460" reach plug for 350 trucks-towing and marine and corvettes (high performance)
that see more WOT running and use this .460" reach plug.
It is not too cold and will not foul. Its just right for your purpose.
Yes it happens to also work very well on moderate supercharged performance motors too.
The R45TS is a a hair too hot for a high compression High performance motor.