My question involves name change laws in the State of: Missouri

I am currently 22. When I was about 5 my mom remarried and my step-father adopted me, giving me his last name. They got divorced about 6 years ago. I have no association with my former step-dad, and my biological father is back in my life permanently. He turns 40 in June and I want to try and surprise him by legally having it be as if I were never adopted. His last name, and his name back on my birth certificate. Is this possible? If so, is a month and a half enough time to accomplish this?