rear end conversion on dodge intrepid

Any ideas how to convert to a rear end drive on the 98 and 99 dodge intrepid? I want to get away from the expense of the regular engine and front drive. What would work in the Intrepid as far as a rear end conversion? I plan to install a Ford or Chevy small block or even a 318 if they will fit under the hood. Contact me if you know of anyone whom has done this or anyone who can do this work. :2cents: