Op, I'm sure a stock BB 383 or 440 weighs more than a early 354 C.I. all iron Chrysler fire Power Hemi do. Do some research to make sure though
I've own and used both, the bare B and RB blocks are heavier than the bare 1954 to 1958 hemi blocks are. Not so on the heads but I have never measure the actual weight of a stock early hemi motor with exhaust manifolds, motor mounts and so on.
I don't remember the advertised HP on the 1956 354 C.I. New Yorker and Imperial motors but I'm going to guess around 275 up to maybe 300 HP. The 1955 331 C.I. New Yorker and Imperial motors had 250 HP advertised and the 1957 and 1958 New Yorker and Imperial 392 C.I. motors where advertised as 325 HP is what I'm remembering now.
The "300" cars that had dual quads and solid lifters motors had around 50 HP more than the single four barrel hydraulic lifter motors of the same year had