I need some thoughts as how to proceed

Hi if your reading this thank you. I just joined this site because I just got a 1967 dart gt convertible it needs floors and the frame rails under the car need replacing. my question is should I replace the frame sections then remove the floor or should I remove the floor to get better access to the needed work. I do not want to the car to scrap metal by doing the wrong thing. I am looking forward to what you have to say. thanks take care.