Comparing the landing distances of the 747 400 and classic “at the same weight”, as you suggested, would only add support if they are landing at the same speeds. Not being informed on the 747 series, I’ll not comment on any different wing aerodynamics that may or may not affect landing speeds.
For the 747-200, Vref = 140 KIAS at 250,000 Kg
For the 747-400, Vref = 140 KIAS at 240,000 Kg
or 143 KIAS at 250,000 Kg.
That represents a 4% difference in "wing aerodynamics" at 140 KIAS and the -400 is actually landing FASTER at the same weight...