Your gauge says you are in the green, that is all you need to know!!!! If it goes up from its normal position, then you need to think.
It looks like a new gauge cluster, so may not be as accurate as the original. (not that it was accurate)
As said, for peace of mind you should measure the water temperature just after the thermostat. You will see the stat opening if you have the radiator cap off as well. There is an opening temperature but full open is a bit higher. This depends to an extent on which thermostat was inserted, should have been a 195 but some mistakenly put in lower rated which leads to increased wear and a cooler heater.
Opens at 195F
Fully open at 218F
You should also have a rad cap rated at 14psi. If any less then you will get boil over at a lower temperature.
Efficiency of the system is affected by radiator cleanliness, coolant, pump etc. This is only a concern if the needle starts to creep upwards and even then only if it hits 250F, the boiling point at 14psi.
For peace of mind I would be concerned if it hit 242F for any length of time, which is supposed to be the top of the green band.
At the top of the band the resistance measured is 13 ohms. You can measure this or replicate it with a suitable resistor, but I just match the readings to what my thermometer tells me.
Bagusjeep got a new engine rebuild, a lot has been renewed. Gauge now goes to 2/3 of Green, approx 220 on the gauge maybe. It measures 205. Happy days if it stays there.