Hi Nick,
sorry for the late answer. The image is not exactly the As 413, but the Arsenal 24H*, which seems to be the same engine, and not the Jumo 212. You have the image in Kyrill von Gersdorff`s "Flugmotoren und Strahltriebwerke", page 83. As said before by Richard, Bruno Lange in "Typenhandbuch der Deutschen Luftfahrttechnik", page 304, depicts the same engine, this time seen from behind. It is interesting to know that this "beauty" was developed by Fritz Gosslau. Probably Richard`s magazine as some hints. Unfortunatelly I do not have a working scanner at the moment, so I can not send the image.
* Bill Gunston states that the 24H-tandem ( two coupled 24H ) was actually run.