I ended up running with a 525i steering gearbox, which is a slightly different design then the v8 version. I opt'd for this due to cost and availability, the v8 version of the gearbox is tough to come by. The 6cyl steering gear fit beautifully in the frame, the OE pitman arm and steering coupler also fit great.
This steering gear box feels great, way easy to turn, smooth with no gear lash or slop. It's so much easier to turn then the original. For that I want to do what's necessary to run it.
Started setting the drivetrain back in place.
It's going to need some work for a header pipe to clear a banjo fitting on the steering gear. I also ended up needing to move the drivetrain forward roughly 1.5" to get to this point
With the relocated drivetrain the headers fit the body & firewall much better as well as the increased room behind the engine makes it much easier to work on. I still need to see if the driveshaft can/will telescope to compensate for the relocated trans tailshaft and I would also need to lengthen shifter linkage. But, the transmission crossmember fits fine utilizing previously unused threaded holes in the body.