most versions of the Sparviero were equipped with PWO.2 two-pitch all-metal propellers, manufactured by SIAI Savoia Marchetti.
the original tech manual scan can be bought and downloaded using the following link:
Please note that the same publisher sells scans of many SM-79 original tech manuals: I am confident you will be able to determine which aircraft series were equipped with alternative Ratier type propellers.
In addition, here is a FB link to https://www.facebook.com/modelpublishingbooks/, the Savoia Marchetti SM-79 Publishing Book project: this group also aimed at releasing accurate scale drawings based on the original airframe displayed at AMI Vigna di Valle Museum.
Got no recent news about publishing of their drawings.
The pandemics safety measures prevent me from hopping to the museum and gathering additional info you might need - sadly.
Nevertheless, hope this helps!