Or, like the rest of us, your factory tach is off by a 1000 RPM's.
Car and driver, in their original road test of an '86 GN said 5000 RPM = 109 mph in Drive.
Pulling a real 5K in OD in a hot air, or even a intercooled car, is a tough trick that would take at least a mile and 1/2 and at least 40 seconds of full throttle from a 60 mph roll... unless it was out on the 1 mile down hill on hwy 89 out west of Wickenburg. You could probably do it there.