1993 ford taurus sho

I have a 1993 ford sho and had no brake pressure for 3 days. After I parked my car and went to leave, it started but will not shift out of park. We replaced the brake booster and tried to bleed the brakes, but the brakes did not have enough pressure to bleed. They were just pushing out air and my car still was stuck in park. The brake lights still work and i checked the fuses under the dash and they are fine. I've been told that the master cylinder may be bad or I have purchased a bad brake cylinder. I would like some advice on what to check 1st and does the brake malfunction actually have anything to do with my shifter? I would greatly appreciate any advice, thank you.