I have had many horses like this come in and I find that their desire to run is a short lived situation.
I mean if a horse has a desire to run....I let them and don't really get into a fight about it.
Run,run,run and then I check in to see if they are at all interested in stopping.
If not we run,and run,and run.
Now we want to stop all of a sudden and no we can't yet.
Run some more and all of a sudden we can stop any time we want as their attitude changes.
Most people that are not accustomed to a good strong gallop go into panic mode and never see what happens on the other side.
It is just fine and the horse tires and slows into a lope in most cases.
Three or four sessions like that and they just stop the big gallop in many cases.
It is a glass is half full or half empty kind of thing and I choose to approach it as half full and enjoy the gallop for a bit instead of hauling on their mouth.
Bits are not for stopping.
"The greatest strength is gentleness."
- Iroquois Proverb