FWIW I used a piece of rubber hose, split it in the middle then trimmed on the edges like a butterfly till I got the feel I liked.
This is simple idea and easily made from home with some thought and trial and error. You will want something sorta soft and when it smashes it needs not take up a lot of room, ibggest reason I cut the relief in my rubber piece.
I can say this is an excellent mod for the brake. I got enough feel that to get full brake I actually have to push the pedal and not just step on it.
FWIW Mine is inverted in a custom steel cockpit, very solid mounting.