I got it all cleaned up with my sand blaster and wire wheel and sprayed some paint inside the box prior to me sealing it up.
I cut off the flange from the new box I purchased and cut out the old flange, got it fitted and welded. Also welded the outer skin in place.
For some reason I decided to grind down the welds on this side and it turned out good. I ran out of seam sealer so I'll catch all the seams after I get some more.