Oil isn't even at it's correct working temperature until it's at 100C.

Those temps on an air cooled engine wouldn't worry me.

Your viscosity rating 40/50 etc is actually measured at 100c

As for those temp gauges. They may not be totally accurate but what they do show is variations. If you're usually running a certain temperature and it suddenly drastically changes, then it's a great warning that something is going wrong. Especially when your oil is low because it WON'T register a temperature you're used to.

You should test your temp gauge in boiling water too. See how far out it is.

same thing here. It's happy between 100-120, sometimes it cooks about at 140. I've got an oil cooler and big bore kit 1000cc.