The usual wisdom is to use a tracking force in the top half of the range (but not usually the top value). The reason for this is that if the tracking force is too low, the stylus may rattle around in the groove and cause mid-tracking distortion.
If your stylus was recently bought by the previous owner, it may well be an aftermarket stylus unless they managed to get a NOS original. You can probably tell, as if it's genuine it should have the AT logo on it, like this:
https://www.lpgear.com/product/ATN12S.html
Apparently, styli for the AT12 cartridges will fit your cartridge. So, if you wanted to upgrade the stylus in the future, you could go for an AT12 stylus with advanced profile like the above shibata. I'm not sure if I'm allowed to put a link to Vinyl Engine on this forum, but there is a thread about your cartridge over there.