I went to switch my oil pressure swich an for some reason

What that looks like is a knock sensor gong into the water jacket. The plug for oil should be just above the oil filter like an inch or so towards the front an dcomes out the side.

If you have aa manual that shows an engine block it should be there. It is la hole that HAS to be drilled inorder to finish drilling the main bearing/cam feed it should be eitehr a 1/2" or 9?16" plug. There should be no wire going to it if there is you will need an adapter for the oil pressure switch.

Use th one on the block, you shol dhave said yo have an engine oil cooler on this. You culd also try the one on the filter housing but I dont 'know whttype of pressure reading it will give. There should be a plug on the block not a hole. Otherwise try to find a manual that gives a picture of a block