The other thing that may be worth doing is discussing with a training Captain what actually is going to happen if you exceed MMO by 5 knots, 10 knots , 15 knots etc
Talk to an Engineer about what inspections they need to do when the aircraft is oversped by different amounts.
Read up on how the aircraft is certified and how fast the Boeing test pilots fly it when determining speeds.
After doing that I am pretty sure that you will come to the conclusion that overspeeding the aircraft by a few knots is something that you will obviously try to avoid, but at the same time is no big deal. The safety of the flight is not at risk if the aircraft momentarily exceeds MMO in the situation you have described.
Now.......go and look at the risks involved with getting slow while at altitude...different kettle of fish.