Don't think I've ever seen a B777 at FL430, or am I wrong?
I have..
..(777-200)...
From memory I think the published ceiling for both the -200 and -300 was 431 but I agree with the previous comments about the -300..it wasn't really a "high flyer" in comparison with the original "light twin".
As eckhard says the 744 was FL 451 but I was only ever in the position on that machine once where weight etc made it possible to go up here but because of time remaining to destination it didn't make sense to do so.