Ok, I guess
I'll post some pictures then. A Duster hood is several inches shorter than a Dart hood. That's because Duster fenders are several inches shorter than Dart fenders.
A '70-'72 Dart hood with Duster fenders. You see the problem right? Your Dart fenders would line up with the hood in this picture. The Duster hood would line up with the fenders in this picture.
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And, if you have a '74 Dart Sport that doesn't have a beak, we really have NO IDEA what hood will actually fit the car, because you could be missing a whole bunch of parts. Or who knows, you could already have different fenders on the car too for all we know. You can exchange the front clip from almost any A-body onto another A-body if you take the whole thing, only one that doesn't apply is the Barracuda. What you can't do is just mix and match parts.
So yeah, since your car is not original, it will be pretty much impossible to give you any relevant information until you post a picture of what you've actually got.