Brake pedal rod for master cylinder - which to use?

I have a replacement master cylinder to use for my 69 Barracuda. I am looking for the rod that connects the brake pedal to the master cylinder that will work with this master. The rod that was in my car originally is bolted to the master and has a rubber boot over where it mates to the back of the master.

For the new replacement master it appears the rod does not attach to anything and just rests inside the recess of the piston plunger (plunger has a recess of around 3/4 inch). The rod would need to look the the end of a pushrod. I guess the brake pedal cannot move back sufficiently with the correct length rod for it to back out.

Any ideas from which vehicle I can get the right rod?

Thanks