The 70 fender buckets will have to be modified to accept the four-headlamp style bolt in mount. You will need the headlamp mounts, four of the small headlamp setups, a 71 header, the complete grille assembly of course, the valance, the valance insert, both turn signals and all of the small supports.
Be prepared to spend around $3500 or more if you can find a decent used grille for 2K or less. Mike Ross has most of the 71 parts that you will need at BE&A parts. You probably won't find many used parts since they've pretty well dried up.
Now to complete the 71 Cuda transformation you will need a fender gill setup, a set of tail moldings and a set of 71 taillights. At least the taillights will bolt right in to the 70 tail panel.