jettison valve - the ZFW for most of the variants varies from 174000 to 181000, with most at 178000 kg [which I used].
I didn't know that the WV 027 variant was for China Southwest. The A340-313 WV 027 aircraft design was varied to operate as a [higher cycle =] short range variant and so they have their design service goal increased to 30 000 cycles respectively 60 000 FH, provided a special inspection/MRB is followed. All the variants have the same max structural payload. Love to know more if you find something.
Pickled Props makes the good point that the two are rather different, and I've got my own strong opinion about preferring the 777 to pax in, but I don't suppose the cargo cares.