1981 front cap on my car

[84LX89GT]

You'll need the fenders off of the earlier car because your car has "fender extensions" that are fiberglass at the bottom of your fender which if you take off the extensions there will be some big holes exposed.
You'll need the hood because your stock one obviously won't fit as you've noticed.
You'll need to use the front bumper off of the earlier car (which i might add is about 40+ pounds heavier because it's all iron instead of being partially styrofoam impact material like the one on your car, plus the turn signal housings are inside the bumper.
You'll need to rewire the headlights, which shouldn't be that hard and also your turn signal lights because the turn signals are inside the bumper. You may not have to extend the wiring on the running lights.
And of course you'll need the new bumper cover with the headlight retaining assembly attached to it.
it'll probably take you a day or two to do all this depending on how long it takes to line everything up, and adjust the hood latch and stuff like that.
Everything should basically line up and the bolts holes should be the same although i may be mistaken. I say go for it, it'll be unique and i think those years look pretty good as well. Good luck,