I have 5 original 273 commando cars here right know of Todds and all are flat tops same as the 2bbl engine. I just ordered another a set of domed from Egge.
I have had so many virgin 66 and 67 Commando and Charger 273's I could not count them. Some with only 50,000 miles on them. All had domed pistons. I have never had a 275 hp D Dart 275 engine and have at least 2 sets of domed pistons and rods in the basement. Maybe the pistons were swapped in your cars when gas octane took a nose dive in the 70's or 80's. Or people swapped the Commando stuff onto 2 barrel 273's. That was what we did to my brothers 67 273 in his Barracuda.
