PDB said: Re-creating the International cut in HD is going to be a hard piece of work for whoever takes it on. Its not just removing the Italian scenes, there are a ton of 1 or 2 second shots to remove also. And then putting in the tiny bits from the International cut. There is a lot to work to do.
It's not too bad actually. In terms of frames, the Mondo seems to be closer to the 2014 BD than it was to the previous MGM one. Most of the time, the Mondo has more frames, so deleting them syncs the two quite nicely. I've almost finished a script that does that. (It duplicates a few frames in places in which they would not be noticed, but these can be deleted easily enough if necessary.) The script also recuts the beating scene, which is the only major difference between the Italian theatrical cut and the extended cut; obviously, the missing shots will have to be color-corrected and inserted from another source.
Apart from that, the English credits can be spliced in easily enough. The shots that have Il Buono, Il Brutto and Il Cattivo can be replaced.
All of this is, of course, if people decide that the Mondo is the best source. If the 2014 BD can be color-corected to people's satisfaction, then the work is even easier. But I'm not yet convinced that it can be.