Gotta say, been a few days since I had to give back the 650i cab, I am pining for one now as much as I couldn't see out the back. It's to the point where I might try to get an M6 cab in individual Malachite Green over ivory to drive on days where I can put the top down. If the top is down, visibility and sizing is fine.
Figured out a driver's license fix in Japan and I found an E39 Alpina B10 V8 4.6L I might be able to get for about $8K with 30K miles on the clock as my 'beater' practice car when I go back to Japan, it's like a punched out 540iA that I won't be tempted to do shit to. It's not the V8 4.8L so that is why it's going cheaper than normal. I'd probably keep it for awhile if I bought it though, and add the nicer car and let my wife drive it. If the head on the Alpina 4.6 is roughly the same as the regular 540i (and I think it is it's just the block that is punched out) I could put an S/C on there..