Calvert Racing sells perches like the ones pictured, (not mine by the way), but i'm sure there are some other sources in the race suspension world as well.
Since you already have things in place, you could probably just add some plate to the existing perches in the area shown in orange. I doubt that slow, on & off welding would warp or twist anything as long as no excessive heat builds up. View attachment IMG_9378.jpg
Some may feel that it's unnecessary, but I wanted to show you a idea of reinforcing that area.
