Here's a location shot, Manfred. (No processing, just converted to jpg.) The church and other buildings face due North. From about midday on the mural is shaded by the building in front of it and there are other tall buildings to the west of that one, too, so I suspect it is probably shaded in the late afternoon as well.
I think there is another building behind the church which might cast a shadow from the east on the mural in the golden hour, so an overcast day is possibly the best option to avoid the shadow. But I will definitely check it out. A lower angle of light might bring other opportunities, too.
_84A1549 by
Foot Loose2012, on Flickr