For those of us not from Germany, the annual inspection is a nightmare. (I spent two years in Germany, and a lot of our personal time in the motor pool was helping guys trying to get their cars past the inspection.) Probably 1/2 of the cars on the road in the US would fail.

I would personally stay away from changing an engine in a car that old under any circumstances, as things tend to get really ugly to work on when they've been assembled for that long.