To answer your question....cz27/24 mags fit in either pistol however.....there are important difference that separate the two...First a cz24 is 380...cz27 is a 32 acp...therefore mags are not interchangeable on a functional level! The major visual difference for the two is the rounded slide for a cz 24 unlike the flat slide of a cz27.....Many people differentiate the two by slide serrations.... A majority of cz24 slides have slanted serrations (Pre-war)....cz27s in the serial range below 20450 are also slanted...however CZ 24 without sn have vertical serrations! So base your identification on the flat/rounded slides....Hope this helps on your search of SA marked mags!
....I have not heard of a cz27 that is SA marked..but I am not an expert either lol!
Always looking for unusual German/Foreign commercial pistols & revolvers with E/N, GECO, AKAH, KABA, etc markings!