I think the SM.79CS variant would be interesting to play with.
It had uprated Piaggio engines and set some records in the pre WWII era. It also was stripped of the dorsal and ventral gun placements.
In the real world, the Junkers Ju-52 was built post-war in France and Spain. What if they opted to produce SM.79s instead and based them off the C model.
The Ju-52 was rather bigger all around, but the SM.79 was a cleaner aircraft aerodynamically with its retracting landing gear and smooth skin.
There could be some interesting re-engining options in that scenario.