Thanks Veeps
I hadn't checked out any freight aircraft specs for load capacity, but had suspected that we were talking "big a/c" (it was late in my time-zone when I posted, after yet another 14-hour day!)
Looked at Foyle/Antonov's web site this morning, as well as Boeing's site . . .
So the AN225 can lift the 747 Freighter
and its load!
Now need to contact our supplier to find out exactly what we are shipping - it's "12,600 bushels", which equates to around 550 cu.m. (I'm told!) but the ANs can carry lots more if the weight is less than 1 tonne/cu.m.
Have passed the London contact to our Gen. Mgr. to do the "commercial talking"
I just knew I'd get my answers from PPRuNe 
(PS - Now I wonder how I can wangle myself a job as "cargo attendant", coz I\'ve never flown flight deck on an Antonov
)