that camera is producing some excellent crisp dense and contrasty B&W images. Mongo agrees with you that it would not be an easy task to get as good results in PP. Even with the use of specialised PP software like Silver Efex etc, it would not be as easy as pressing your shutter button. Even if the result could be duplicated in PP, it would take about 20 mins to a half hour per frame to achieve, if possible. Mongo has had reasonable results but starting with a colour image. There seems to be a lot more adjustment on the conversion to B&W than starting off with a B&W image. At least, that has been Mongo's experience.
Paco, you are on a winner with that camera and you may find it is not possible to get that result without a big effort out of camera. So, the answer to your question is, "probably not".
As a matter of interest, can you tell us the B&W setting on your D750 that give you these results ?? would love to duplicate them in Mongo's cameras if at all possible (unless this is purely a D750 thing)