Skiesful,
You're right, the max sink at max weight is 360 fpm.
I fly the -200 which max lands at 630,000. Was thinking the -400 had substantially higher gross weight limits for landing as well as takeoff. Not trying to wiggle, but those numbers are as old as the airplanes. If I am landing a 747 above max gross weight, I'm going to make the touchdown as soft as I can. A normal landing at 300 fpm is firm at any weight.
A key point I was trying to make is that in this incident, with the aircraft below normal landing weight, the crew discarded the need to dump during the takeoff brief, so it wasn't a factor. I agree that an airplane on fire needs to get on the ground and landing heavy is much better than delaying to dump as a rule.
Whatever you do, you're going to be standing at the end of the long mahogony table with no ashtrays explaining yourself.