Okay, i have a tiny bit of information.
So a friend of mine talked a diff shop, the guys i was originally going to send my diff out to. They are a pretty well known diff company on bfc. He told them what i was what i was doing, and they actually said that's how they do their e46 diffs aswell. they grind out the housing to fit diffs in there, so they could do custom diffs. As far as the bearing issue, and shimming it out. they told my friend that i'd need a special cnc plate to make it work well.
I don't mean to tease you guys, but i haven't talked to the shop personally just yet. I'm going to try and get out there next week sometime. I just wanted to keep you guys updated with every bit of information i have.