https://collectability.com/learn/collectability-in-depth-patek-philippe-perpetual-calendar-ref-3940/
The Roman numerals reference is similar to 5327 despite the fact that it’s 36mm. 5740 has the 240 movement and is proportional despite its larger size. So it’s interesting that 5327 is sort of singled out here. Perhaps it’s the design. Either way, it’s super interesting perspectives on a variation of the same movement (which is my favorite Patek movement btw).