My '74 Duster with just one race seat weighted 3060lbs Aluminum heads 451 short deck big block. 6pt cage All steel tilt front. So yes. With a SB and the lightened body parts? 300lbs lighter. Should be about right?
It seems to me the guys that say a 400/440 can be as light or close to a small block always compare a bbm with as many aluminum parts as possible, to an all iron sbm. They seem to forget that aluminum parts are available for a sbm too!
To the best of my knowledge, a comparably built (as many aluminum parts possible, short of an aluminum block)bbm weighs about 100-150 lbs more than a sbm, assuming both with a 727 [904 sbm is lighter].