If you Z your frame, you can BD your bed and keep the 2wd floor while setting the 4wd sides on it.
If you are planning to BD your truck in the long run then this will work great for now. You just have to figure out how long of spacers you need between the frame and bed. If you are not planning on ever BDing your truck then you should step into the nearest bathroom and look at yourself in the mirror and ask "What am I really doing with my truck" . Then proceed to BD your truck. -ED