Hello Bill
It is my understanding that as this was a trainer rather than operational version of the Mistel it was normal for the guns to have been removed to save weight including the cowling mounted MG 131 machine guns. I have no idea if the fairings were added post-war but I do know that when the machine guns were removed from the Fw 190 A-8/R8 assault fighters it was normal to add the fairings so quite likely these were fitted prior to capture. Concerning photographs of this Mistel component before it was repainted, the available information that I have seen is rather confusing as to which aircraft are actually depicted in the photographs of the examples captured by the British. I have seen various photographs of a Fw 190 A-8 paired with a Ju 88 A-4 which I am posting below and others of a Fw 190 A-8 paired with a Ju 88 G-1 with a glazed nose. Interestingly, the spinner of the upper component of the first Mistel is identical to that of the Imperial War Museum example so perhaps it is the same aircraft.
Horrido!
Leo