This is unfortunately not a bolt on affair. Even if I were to weld up the holes and re-drill them, they would essentially by right on the rim of the backing plate and I would not trust that mechanically. Any more work than simply welding and re-drilling that bolt pattern is enough for me to just go the adapter bracket route even though I was trying to avoid it.
The only other possibility is that the 2-pot rear backing plate has a smaller opening and therefore more material to re-drill but that doesn't solve the e-brake issue which is the whole problem.
Ben