Easier and faster: remove the pushrod before removing the master cylinder from the car. You take off all four nuts holding it to the firewall, pull it forward (which will move the brake pedal to the floor), put a chunk of wood or similar between the master cylinder and the firewall, go in the car and give a stiff pull upward on the brake pedal. Pop goes the pushrod, still attached to the pivot at the top of the brake pedal arm. Nice to have a helper to grab the master cylinder when it wants to fall away from the firewall.
I have been known to put a master cylinder w/pushrod on the firewall and loosely put the pivot bolt thru the pushrod to use this method rather than hunt up a slide hammer and mess with the vise.