Yes, it's just a matter of changing the entire front clip, as you described. I've done it converting early & later Dusters to a Dart Sport. '74 should have standard front bumper brackets like earlier ones.
Actually, if the car was built before December, it might not have the standard bumper. For the '74 model year they actually started with shock mount bumpers, then went back to standard bumpers in early December sometime. The rest of the '74 model year ended up with standard bumpers. But the cars made before December won't have the mounting holes for standard brackets. The cars from mid-December on have mounts for both the standard brackets and the shock mount brackets.