I have just called the Elite line, and the agent said that those "blocked" seats, at least appearing so online, were actually avaialable. So I got my favorite (and everyone's?) 73AB both directions.
The Elite or the premium seats in the nwa.com seatmap for the 747-400 are actually the L/D, rows 1-4.
Well, the truth holds again: "When in doubt, call the Elite line."