The "so called" new engineering on the 426 Mill
was simply a bore change and factory upgrades
(stronger internals and valvetrain pieces) along with an increase in compression. Basic hot rod
technology by Chrysler to increase power output.
Same tech was apllied to the 440. Chrysler never
really retired these motors, they were shifted over to the industial/truck division. 440 was the
top engine due to it's cubes to power both cars and trucks to save money, as big engine evolution
started going downhill due to the looming oil situation in the 70's.
Otherwise we would have more choices again in engines.