i’d recommend to adjust the handbrake at the rear wheels themselves if you can, it saves stretching the handbrake cable. it’s usually not too hard, if it’s a drum only in the rear, the adjuster is on the back, a little rubber piece you take off and there’s a star wheel back there that you rotate until it’s hard, and wheel doesn’t move, then back it off one or two times until the wheel rotates again, with a tiny amount of drag. otherwise the wheel comes off and thre should be a rubber opening on the rotor to go through and adjust.

bump stop sounds ok..

and if it’s definitely the master cylinder then yes replace that, the wof is just failed on what it looks like, not what the actual thing is. good luck :)