Cage paint and rust repair!

I cut out the square and make a square the is 3/8” bigger all around. Then make another square that just fits in the hole. Plug weld the bigger square on the back of the jam around the perimeter of the hole. After welding the cage for the striker nut on the back. Then plug weld the second square to the other square and weld the seam. Doubles the thickness of the jam in that area. Make sure you you mark cross hairs outside the work area so you can locate the new round hole where the old one was.