You can cut the brackets, lap them, and re-weld. One other thing you might want to do is remove the rubber filler panel between the bumper and the body. Only 73-74 used that piece and it looks a lot cleaner if you remove it. 70-72 used a metal piece between the bumper and the body but it is very hard to see if you don't know what you car looking for. THey are available new I believe.
You can also remove the triangular braket on the rear valance that was used to space out the lisence plate. 70-72 didn't use that spacer bracket.