I'll stick my chest out.
Not done a BMW motor swap as I have no need to. I do do all my own maintenance including clutch replacements, head replacements, seat rebuilds, halfshaft replacements, blah, blah, blah.
In 1981 I replaced the engine in my 1972 Pinto with a used engine (I had a spare). It was late January and about 20 degrees outside, on a gravel driveway. Do I earn my stripes? It was after all the German Ford 2.0L.