TGs 744s come in 2 configurations, one with a newer/decent, the other with old C-class. While it is a hit and miss at times, generally the older seats appear on transpac routes, the newer on Asia-EU routes.

Depending on your connection time at LAX you could check your luggage (if you check at all) only to LAX and try w/UA to allow you on their NRT flight. While this is technically not possible, they might still allow it, since you're holding a UA ticket and change to a UA flight.

Good luck!