There are alot of things that would need to be changed. The 1972 fenders have bolted in metal headlight brakets, they are welded in on 1970 and configured differently.
The 1970 turn signals are now in the grill requiring a different 1970 only lower grill, and now requiring a different headlight harness for the turnsinal change.
The header panel is 1970 only and would need to be changed.
It might be possible to fabricate ways around the header and headlight bucket situation, but it may also be more trouble than it is worth.