The bracket is getting much closer! The whole assembly got bolted back up to the car and the bracket was marked again. Not enough material had been removed from the bit of angle iron, so I ground that down some more. To make sure everything was held at the right angle, I put the body-side mount in place on the workbench, clamped the other plate on, and tacked it in place – very slightly to avoid heat-damaging the motor mount and insert. Some more booger-welding later, and now I have this:
I’ll bolt the whole thing back up again, verify the location of the engine versus the existing bolt hole, then mark the other bolt hole, unmount the whole apparatus again, drill the hole, and mount it all back up to make sure it’s right. Assuming that works out, then I need to clean up the existing welds, trim the bracket down to prevent sharp edges, and add some gussets for strength.