273 super commando #4 and #6 not firing

The Mopar 273 was Chrysler's first engine in its LA series of small block V8s. The 273 was introduced in 1964 wit a 2-barrel carburetor and made 180 HP. In 1965, a high performance version of the 273 called the Commando was introduced. The 273 Commando had a hotter cam, 4 barrel carb, and made 235 HP. In 1966, a limited edition racing version of the 273 called the Super Commando was offered. The Super Commando was equipped with steel tube headers, a 700 cfm Holley 4-barrel carburetor, a high lift mechanical camshaft, and made 275 HP. Production of the 273 spanned 6 years, lasting through the 1969 model year. The low end version was replaced by the Mopar 318, while high output versions were replaced by the Mopar 340. I wasn't sure what to do with it since I'm thinking of replacing it. The more I think about it, the more I want to fix my problem or rebuild it. In spite of the small size, the Mopar 273 is a good engine. As the first engine in the LA series, it's also an important piece of Mopar history.