The larger props of the Osprey may have greater efficiency over smaller props. The high wing of the Catalina seems to have enough room for larger props. The original PBY had a range of over 2000 miles and was amphibious. Could this old design find use today with modern technology?
The engines on a PBY-5A Catalina are spaced only about 15' apart. The V-22 Osprey rotors (propellers) have a diameter of 36.1 feet and are much too large.
The engines would have to be moved more that 36' apart for the 18' blades to clear each other. The “high wing” of the Catalina is only about 10' from the water during water operations, and about 14' from the ground during ground operations, so that presents additional clearance problems.
To scale, putting V-22 props/engines on a Catalina, would look like this: