Having seen these in original releases (Khartoum Cinerama 70, Zulu 35mm) and on LD, I thought I would make a few comments.
1. Zulu has apparent edge enhancement but still watchable.
2. Khartoum looks somewhat murky. Image is too blue but can be corrected (my opinion).
3. Both have decent 2.0 soundtracks, why this is "best possible" is beyond me, especially for Khartoum.
4. Khartoum's mattes and special effects are substandard even for 1966.
1. Khartoum is something of a mess. Heston give it a try, Olivier can be brilliant but seems uninvolved. The fact that Olivier was not on location is obvious.
2. Khartoum's score is a pistache of themes nearly copied from films like The Great Escape, Cleopatra, and Lawrence. Doesn't work for me.
3. Zulu is a very fine film in every respect. Interplay between Baker and Caine is very good, entire cast is involved, Zulus are totally credible. Cherish this one.