I was mistaken. Dad’s hemi was the D-501.
“The engine was actually a high-performance Chrysler 354-cu.in. engine that had been used in the 1956 Chrysler 300B; the 10.0:1 compression, dual four-barrel engine made 355hp at 5,200 RPM and 405-lbs.ft. of torque at 3,200 to 3,600 RPM.”
Not bad for 1957.
https://www.hemmings.com/magazine/mus/2010/06/1957-Dodge-Custom-Royal-D-500/3334701.html