M8, baby; I want an M8 from these people. According to Wikipedia, there was an amplified M8 at Copacabana Beach (Rio) that drew a quarter-of-a-million people! But hey, M2 is a big start.
I'm pretty sure that Neschling did a whole Mahler cycle there in Sao Paulo. That's a big, relatively "boomy" hall - part of an old train station that's still being used - so it should be just perfect for the end of M2. It's not surprising that the timings are on the longer side of average. M8 would fit that hall perfectly. And just as an f.y.i., BIS just issued a box with ALL of the Villa-Lobos Choros and Bachianas Brasilieras included, with these very same folks, recorded in the same hall. They're really great players in that orchestra.
That's a great box set, by the way (Villa Lobos)