Brake master cylinder ??? (pics)

I have been converting my car over from drum brakes to disk brakes on the front. I have been posting on another thread. Start at post #17.

http://www.forabodiesonly.com/mopar/showthread.php?t=27418

I have got everything ready to go and trying to mount the new disk brake master cylinder and removing the old drum brake master cylinder. I can't get the dang push rod out of the old master cylinder. I tried removing it while it was still hooked to the brake pedal, tried removing it from the master cylinder and finally remove the internals of the master cylinder without any luck. The new master cylinder is definitely a bigger bore size even though they look the same in the picture.

What do I need to do here? Get a adjustable master cylinder rod? Get the mopar later model master cylinder?

Cuda boot area 011.jpg

Cuda boot area 012.jpg

Cuda boot area 013.jpg