Oil pressure switch

On a 225 slant is there any other source where a mechanical oil pressure gauge can be hooked up?

I was going to tee at the oil pressure switch and add a pressure gauge, but the stock switch is super tight.
I put a socket on it with a 1/2" rachet, at it does not want to budge. I am afraid to break the stock sending unit off if I put any more pressure on it.