This partial quote implies that a fully restored version exists (in some publicly-viewable form), but I don't see any details:
[At long last, materials for some of these missing sections have been found and re-inserted into the picture under the supervision of Leone’s family and surviving collaborators. The work has been completed by the magnificent team at Cineteca di Bologna and L’Immagine Ritrovata, and it has been wonderful to witness this enlargement of Leone’s vision, step by precious step.” —Martin Scorsese, Founder and Chair, The Film Foundation]
The 2 disk special edition is 229 minutes... I saw it many years ago on Netflix (before they had streaming) and I remember it being extremely long, like: had to stop in the middle to get the second disk delivered long, so I'm pretty sure I didn't see an 139 minute cut.
well, for whatever it is worth, the runtime of the non-extended cut which is available for streaming is equal to the runtime the article mentions as the full length version (229 minutes)
As I said, I saw it a long time ago (and I'm no movie expert), but me and the friend who watched it with me agreed the 229 minute version was pretty good but could have been better with some editing to cut the run time... though we didn't have the Cannes version to compare it to (or the knowledge that that version existed)
edit: oops, I guess the theatrical version, not the Cannes version.
[At long last, materials for some of these missing sections have been found and re-inserted into the picture under the supervision of Leone’s family and surviving collaborators. The work has been completed by the magnificent team at Cineteca di Bologna and L’Immagine Ritrovata, and it has been wonderful to witness this enlargement of Leone’s vision, step by precious step.” —Martin Scorsese, Founder and Chair, The Film Foundation]