However, if the journey in mind is the BA 176, I think you'll find that seat plans 747-400(1) and (2) are relevant, as to my knowledge all the JFK flights are now including WT+. The other one, just 747, is perhaps in the minority. Row 39 does not have a full row of seats!
Per Ardua ad Astra! ........ Honi Soit Qui Mal y Pense!