We ran Delco commercial plugs in race engines back in the dark ages. The center electrode and the ground were both heavier material than regular plugs. Those plugs will have a "C" prefix before the number, such as "CR44S" etc. Haven't seen any in a lot of years, but if you find some in a "new old stock" situation, grab 'em! They definitely outlasted regular plugs in a round track engine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!