Seperating master cylinder piston from pushrod (66 Polara)

Hi all, new member from CT. Any tricks to separating the brake pedal pushrod from the MC piston? It's obviously a press fit onto the ball end of the PR... I figure just manhandle it and pull it apart, maybe heat up the piston a bit to expand it. I searched the forum first and nothing about it. Looking at the FSM, it says to not to separate the two. But the rebuild kit I ordered comes with a new piston. Should I leave the piston on and try to slip the secondary seal over the front of the piston? any advice?

thanks.