as all i see is gaps no welds where they should be welds if your going to do that at least weld the underside to the new sheet
with you priming it you now need to go back to clean metal to weld it all up its more of a swine to do now with something like this to clean it all back off
I replied to your other thread, if you could clean the edge of the old metal and weld it to your new plate it would be passable. Finger file with some rough grit belts would do the job. Next time take all the old inner sill off up to the lip it is spot welded to and get the double layer of metal down to single it will make the job longer but a lot easier to repair.