I'll take a different tack, based only on these numbers:
TOGW = 875K#
Acceleration = 7.3 ft/sec^2
Gravitational accel = 32.2 ft/sec^2
Vr = 270 ft/sec
Speed at which thrust numerically equals HP = 550 ft/sec
Then:
Acceleration in G's = 7.3/32.2 = 0.227 G
Thrust to achieve .227 G = 875000*0.227 = 198400 lb
Vr as a fraction of 550 = 270/550 = 0.491
HP at Vr = 198400*0.491 = 97381
IMPORTANT: The horsepower in this example is NOT constant. At the instant after brake release, horsepower is ZERO. It increases linearly with speed; the value cited is the number at Vr.