Hello,
I follow this conversation with great interest because I myself have been waiting for this event for 30 years. Fervant admirer of this period, I put this link that you must surely know but in case!

It is on the Siege of Tuyen Quang (1885) narrated in great detail by Georges Blond on his book on the Foreign Legion dating from 1964.
Well when the figures will be available I think I would throw myself on for a good acquisition, Ah black flags in 28mm on a table! The dream becomes reality!!

One more thing, look at this site although originally the name is about the onslaught of Peitang Cathedral during the siege of Beijing, there are plans on the site about the Marine troops and plans to make a gun boat and a boat to accompany them.
http://sylvain-figsethistoire1914-1944.blogspot.fr/2015/08/?m=0Cheers!!!