I don't know if any of my 440s - or 383s, for that matter - in stock or near-stock form did better or worse than 14 MPG average.
All except 2 B-bodies, with the 2 being C-bodies.
Not that I was concerned about MPG, really, so I don't recall checking only highway MPG on the BBs.
My SB cars did better, as much as 17-18 highway MPG when I checked.