I guess I should’ve done some research… the 7.3L version of the M120 was produced by AMG and used in a handful of SL73’s, which does show up in actual Mercedes literature. A handful of S73’s were built but were truly special units, sometimes commissioned through tuners like Brabus, and some going to the Sultan of Brunei.
And Zonda did use the M120 engine in 6.0 and 7.3L displacements.