If the goal is making the car lighter, the ‘72 is already lighter. Even with aluminum reinforcement and bumper brackets the ‘76 front and rear bumpers are heavier than the ‘72’s.
The only thing worthwhile to swap would be the trunk lid with the aluminum inner panel. But even that doesn’t actually save that much weight.
And yeah, making the ‘76 hood fit would mean swapping most of the front clip and modifying the frame rails.
If you had a ‘73 it might be worth doing. Swapping a ‘72 to ‘76 parts is going backwards.
