Difficulty of changing valve body?

Hi guys. I know absolutely nothing when it comes to transmissions. I have a 727 that I recently purchased and it has a reverse manual valve body in it. Would like to go back to a stock valve body so I can simply put my car in drive and go! Also I have no kickdown linkage on my 383 so I know I will also need this to make it possible!
Any tips for doing the swap?
Thanks