After the 911 got too valuable to play on the track, I built a e36 track toy (although I haven't had time to track it)
Started with a 97 318is, my local BMW dismantler supplied me with a full M3 suspension (thanks to drift kids wrecking them). The M60 4.0 motor came from a 740IL and 6 speed tranny from a 540 sport. Brakes are 996 brembo on e46 m3 rotors (bolt on kit). Its a hoot to drive.
Next bad idea has been the supercharged m62 4.4 I've been building for the last year. It goes in this weekend.