If I read it correctly, everything is interchangeable, EXCEPT the date mechanism.
But your mechanism basically work, you "only" have to tap the case ;) It might be worthwhile to investigate the problem. The date ring has to move without any resistance, and is apparently spring loaded.
Check the mechanism for any dirt or excessive oiling. I "repaired" the day-date mechanism of my Omega Speedsonic by carefully removing all the oil from the day and day ring. (someone really overdid it with the oil) I doubt it needed oil at all.
Check the "springloaded action" of the mechanism, maybe a little bit careful bending of a spring is enough?
And show lots of pictures of this amazing watch :)