auto to 5spd conversion question

cool. i may have to pick your brain on this a little more. i am looking for a 4 spd. duster to build for track use,so i might put the 5 spd in my 71. i hate to cut the floor too much,but oh well!
Ask away......keep in mind that the trans that is in my car is a gm4l80e, it is a VERY large unit......