Brake pedal is really stiff

I let my master cylinder go all the way to the floor when I bleed my brakes which I do about every two years. Never had a problem.

And just putting on a master cylinder the parts store books say to use is not gonna cut it. Figure out what bore you currently have and post that size up. On my car it came originally with a 1" bore and one needed two legs to stop the car. And that was with everything in the entire brake system replaced, including hard lines, and pressure bled. Swapped to a smaller bore problem solved.

Also, size of wheel cylinder bores would be good to know too. Kinda tough to figure out what you have over the internet without all the info. 9" or 10" brake system?