The OAG pocket flight guide now shows the UA 801 as a 744. I'm not sure about the configuration, but I would imagine it would be quite a big J class; when UA had 747-200s on the route, it had two dedicated -222Bs operating and they had large J class cabins. In any case, this would be quite a busy route for Business Class. Looking at the JP airline fleets, there are six -400s with large three premium class layouts (N171-176UA), configured F36J123Y142. I'd be surprised if it wasn't one of these, but let us know when you come back?
As for PTVs in Y class, dream on!
(I doubt it, given the problems with Y class on 777s, as referred to in previous threads.)