i have two pump gas 440's with iron heads. both use kb184's. one has 906 heads, the other mopar stage 5's. both are 9.3:1 compression. one has a mopar 272-.455 cam, cranking cylinder pressure is around 180psi and it can be finickey on 93 octane. it wants the "correct" tune-up, not very flexiable. the second uses an engle k65 mechanical cam and cranking pressure is around 160psi. its a lot more forgiving on tune up with 93 octane. likes about anything you throw at it. i use mopar electronic ignitions with vacuum advance on both cars.