Strange situation on rear brakes - 67 Barracuda

The a body axles have a shorter distance from the wheel mounting face to the
housing flange face than the donor brake parts car had. These axle shafts weren't meant to hold 2 1/2" shoes. This is why the washers were required to make up this difference.
You could change to large bolt axles and the brakes would fit correct. But your wheels would need to be large bolt pattern also.
Is this a 8 3/4 or ?
If you are working on a 8 3/4 It would be a good time to change to big bolt pattern. Otherwise
You need to get those brakes off of there.