If you cannot find the specs for your cartridge, just try as many combinations on the phonostage and pick the one that sounds best to your ears.
Not sure how old or what state your cartridge is in, you will need to replace it at some point. If it’s a MM you will need to replace the stylus and if it’s MC you will need to replace the whole thing, not knowing will make it’s replacement difficult. You are better off replacing it now with a known one and you will be able to set the loading properly.