66 Dart questions

How hard is it to change a 66 Dart from a /6 3 speed manual on the column to a 318/340/360 4 speed in the floor?? Of course I know I would need the motor and trans. :) Do you have to change the K member? Does the 73-75 model A body disc brake set-ups interchange?? How about the later 73-75 8 1/4 rear ends do they bolt in??