Has it occurred to you that whilst 200 Tonnes is a very light weight for a B747, 400 Tonnes is at or close to maximum for most variants?
Whilst 200 Tonnes can easily be accommodated using the normal V2min speed schedule, it may be necessary to resort to the "Increased Speeds" or "Improved Climb" speed schedule at very high weights, whereby V1/Vr/V2 at 400 Tonnes will be somewhat in excess of the normal speeds formulae. This will account for the apparently high Takeoff speeds at the higher weights.
Regards,
Old Smokey