Got the manifold back. They ended up not using the old tab. Instead they formed a block of weld at the end of the manifold. Reason was the weld would be too weak. Had to grind away an inch of weld.

So now I have to grind away the excess weld enough so that the mating surface can be trued. After that drill a new hole. Once that's done then I can grind in the contours and get it as close as I can to stock. I'll use a Dremel tool for that.