Yeah that’s a different story.
The ‘74 quarters are different, there’s no flange in the bumper cut out area. So, you can pull the bumper in by mounting an earlier bumper on standard brackets. But there will still be a gap that the 70-73 cars don’t have.
I did this conversion on my ‘74. The first time through I just made some brackets to replace the shock mounts, collapsing those is more trouble than it’s worth. That allowed me to use the stock 70-73 brackets. Here’s the post with that info
My "new" '74 Duster- or why I need a project like a hole in the head
The second time around I cleaned it up to make it look more factory for 70-73. I filled the holes for the old shock mounts and added a flange to the end of the frame rail like the early cars to the to get rid of my homemade brackets. I also made a filler piece to mimic the looks of the early quarters, so at least at first glance it looks right. Here’s that post and pictures. Title shows up the same, different post I swear.
My "new" '74 Duster- or why I need a project like a hole in the head
