I reckon you know that the 54 331 Chrysler had better heads than the 51-53. Also, it had Chrysler's first four barrel (in the New Yorker Deluxe). And 235 hp, which at the time was the highest in the industry. That got eclipsed pretty quickly, though, not the least by next year's Chrysler 300, which had 300 hp from the same 331 cubic inches, with two four barrels, higher CR and a hot cam. And then 375 hp only two years after that (with 392 cubes). The "horsepower race." Heady times for those, like my Dad, who grew up in the Depression with cars that mostly had top speeds of maybe 80-85 mph.