To actually do it, I would think that it is not that hard, it's just a matter of finding a '71 nose that'll be difficult. They have reproduction fenders but the grill will be harder to find, or more so expensive.
If you can't find the parts you need separately, you may want to look at a '71 parts car with a good nose then swap over the '71 and '72 parts then sell the '71 parts car with the '72 nose on it. Just my
.