273 super commando #4 and #6 not firing

I owned a 72 Ply Valiant back in high school, sold it and now that I'm older I wanted to get one like it. I ended up getting my exact car back, lol only now it has a 273 commando in it or at least thats what the man told me. I don"t know much about that kind of motor. The car starts right up and sound good but has a slight miss, so I took one plug out at a time to find out where. Turns out both #4 and #6 are not firing at all. Plugs look fine no oil. I moved plugs and wires around from cylinders that were working and still no fire on #4 or #6 Cap and rotor look new. I don"t know what else to do :banghead::banghead: