I picked up a moderately track-prepped (but street legal) '01 BMW 330i in August, and I'm in the process of stripping it down to the bare essentials for a track-only car.
The interior has been reduced to just a dash, front seats, and four-point driver's harness so far. I'll probably delete the a/c in the spring, remount the instrument panel without the dash, and upgrade the brake lines to braided s/s. A cage, racing seats, and five-point harness will be added at some point.
...and Sacha has said "go" to transforming her '84 in to a track-only car. Apparently we can't share.