Remember that rated TO thrust is actually developed at just over 90N1 in the MS2002 models. Full throttle gives you far more thrust.
You can use AirEd to see why - see Thrust factor vs N1 & mach no. At full throttle you get about 133% of rated thrust, or 75,000lbs of thrust ea.
I don't find these MSFS models very accurate generally speaking - few models out there are quite accurate - partially because of FS limitations and a tendency to only target certain areas of flight modelling and following stereotypes (such as all airliners are very slow to respond to roll - rubbish - Project Freeware once had probably the most lazy 737 I have ever flown - I've flown the real sim, it ain't that lazy). Then again, you look at the MSFS aircraft manual, and a bit of it really does read like rubbish
So ideally to get the most accurate thrust in FS, you should use the TOGA button. As a guide, 100% rated thrust in the 734 is developed at 93.5N1 - you can actually adjust TOGA N1 settings in the aircraft.cfg file.
Remember (as tempting as it is), aircraft rarely ever use full thrust. Try and fly the 747 a bit more realistically, and it should behave a bit better.