If you have oil pressure the shaft has to be in right.
No way for the oil pump to turn without the shaft.
If the shaft were in wrong you would have 0 oil pressure.
It is common for oil pressure to be high at first start up due to cold thick oil.
As the engine warms up the pressure should go down.
Taking the shaft out and putting it back in has no effect on how much pressure the pump builds.
That is the pressure relief valve in the pump's job.
So if the pressure stays high even after warm up you either have a bad gauge or stuck pressure relief valve.