So it looks like we are doing the same thing. I too have the 01 sport, front end stripped, subframe cleaned, painted etc. Was reading about swapping in the m5 steering box, contemplating grinding off the tabs... and rewelding for the m5 box.
So my question for you, how are you going to handle the wonderful world of electronics ?
Do you have the e38 specific shifter arm and selector rod ?
It seems in euroland the e38 was manual up until 1999, and there might be some unique challenges with cars post that. ( Pedal assembly, shifter mounting brackets etc )
Anyways, seeing as we undertaking the same beast, figured we could combine some brain power.