Thanks. According to that, both use CAN bus and appear to be wired about the same. There's a couple pin differences and an additional connection on the 8HP for tiptronic (I think). None of that seems particularly worrisome.
At least on the V8, the transfer case bolt pattern does look the same to me? See these two auctions
https://www.ebay.com/itm/2007-2010-B...cAAOSwEFhdpLeq
https://www.ebay.com/itm/2011-2013-B...8AAOSwz~RdI3SR
On the plus side, I can reference a 2013 xDrive35i. I'd like to keep the swap as simple as possible so if the original transfer case can bolt on and the original driveshafts can be reused, that would be fantastic. If I ask really nicely, I might be able to get a CAN bus capture from the 2013 which would definitively answer if the messaging is the same.