I had a mess with mine: all 4 bolts were broken off. The machinist removed them, but I can't remember what he said he did for repair (whether he tapped the existing holes or installed helicoils). Then, between being warped and probably not bolting together perfectly after the repairs, he had to weld a couple surfaces to build them up, and then machined it all flat. When I picked it up, it was all assembled with new bolts and machined. He said to just install it as-is. Based on that, I'm guessing you'll be fine to just have it machined as an assembly.