Thanks for the replies, but I want to make sure we are speaking about the same thing, so I took some pictures. The bridge is marred up, yes, I know, but I am going to strip it and powdercoat it so no worries there. The thing about this is, the nut is nice and long and fits almost all the way through the rear bridge, that is why I drilled out both sides. You can see in these pictures a view of the back of the bridge and the front of the bridge. Also a picture of just the drilled hole. I have a lock nut with the brake assembly that I will put on the back side of the bridge between the nut and the brake assembly, so it should hold it nice and snug.
When you look at the pictures, does it look like there is enough material to hold? Or does it look like, with hard braking, the material that is there will end up breaking off or stripping out? Basically, does it look like this setup is safe?