OK, as someone who has the movie several times in 35mm "scope", Ultra-Panavision 70 (this past decade at the Cinerama Dome), on Laserdisc and DVD, AND on MGMHD, here is my take. This is definitely made from the same master as the MGMHD showing. The opening credits exhibit the same bad wear and fading on the left hand side of the frame, everything else is excellent. Far more information is revealed on both the left and right side of the frame in every shot then what I've seen in any 35mm scope source. This looks like the same imagry exhibited in the 70mm print at the Dome. Only two things are missing from that 70mm print on both the MGMHD and the Blu-Ray, and that is the EntreActe (the music leading into part two) and the police calls (that played periodically through the 20 minute fixed intermission at the Dome - it was actually 20 minutes of black leader with DTS timecode syncing up the calls - a series of three calls repeated twice). Its too bad the Entracte is AWOL here, especially since it was included on previous home video versions. At least the "overture," or song, was returned. It had been missing on the previous DVDs. I think this accounts for the 162 minute and 159 minute discrepencies.
The actual pictorial part of IAMMMMW was what most people saw not only in general release but also during MOST of the roadshows is intact here. The film was cut little more than a month after opening and this is the way it ran in most cities (with the added Entracte, of course. The police calls were allegedly dropped early on as well. I thought they were a little underwhelming when I first heard them).
yes it's glaring omission, since the 70mm print I saw at the AFI Silver in 2002 had the police calls - I don't remember the print being that wide at 2.76 - was the 70mm prints reframmed to the more common 2.20 aspect ratio?