273-4 spark plug question

I messed around with plugs with my 340 back in the day, ran like **** with anything but the 9’s. I would say you need to follow manufacturer recommendations. I would call jegs or summit and tell them you need a plug the same heat range as a champ 10 for your commando 273. When I had my hot rod dart, 318 w/x heads and a wild crower cam they sold me accel plugs and it immediately ran better.