K31 Zero/Sighting info needed

I have a K31 I inherited and intend on taking to the range soon, looking for advice on zeroing it (honestly it may already be but I like to be prepared).

My local range has 25,50,100 and 200 yard targets. From what ive seen the Swiss had these zeroed for 300 meters. Im just looking to be able to hit what im shooting at for 100/200 yards. Should I just attempt to zero it on the 100 yard target, or am I going to need a different front sight post?