I think that was a crate motor comparison where they put the available crate motors from each manufacturer in a similar car.
HOT ROD 1992 OCT - CRATE ENGINE SHOOTOUT, VETTE, GTO - 1990-1999 - JIM'S MEGA MAGAZINES
Sure seems like Hot Rod did an article where they tried to build a 340, 350 and 351 to stock specs and compared them though.