Where the oil filter is on the very bottom of that there is a port that is plugged. You can remove that plug and run your oil pressure gauge from there. Just be aware that there is not much room down there, so order your fittings correctly. You can see it if you jack up the front end and crawl under the car and look up to where the oil filter is located and you can see the lil plug.
Actually, I removed one from an old motor that I just junked and I can take a pic for you if you like so you can see what I am referring to later on today.