Holley 750 stalls while hard breaking

Put the secondary float setting back the way it was, raise the primary a hair.
Don't brake so hard unless it's an emergency. A lot of older carbureted vehicles would die during spin outs and so on. G force ..Gravity. That's why happens in a non pressurized system, unlike fi where its pushing fuel through a return and no vents sloshy bowls are involved.
But mostly it sounds like the fuel is going away from the primary jet and it gets air.
Another member suggested jet extensions, that's a little much but I think he is on the right track.