That is probably not going to happen easier Poke-Artist - sta files are savestates aka dumps of the relevant parts of memory where sav files are the saves the games makes aka the custom format each and every makes a different version of to hold the relevant data.
Now you could load a sav file in an emulator, run the game and make a savestate (quite often they do vary a bit between emulators but each should contain the relevant information to convert it).