If you do use the aluminum wheel tubs (they are lighter and easier to fit), I would also cut another piece of aluminum (0.040" thick) to use as a liner to help prevent dents and dings from appearing as easy. The aluminum wheel tubs are usually about 0.032" thick and A.R.T (Applied Racing Technology) sells them that are 0.040" thick.
If you are going through all of the work to back-half, I would put the 4-link under it. They take up less space, better for resale, better for driving on the street, and better for when you take it to the track.
Just my 0.02
Later,
Bill Mitchell