Low Oil Pressure in 2.3L 5 Cylinder

So I finally got the fuel pump working and started the car but I can hear the lifters clicking and there is a low oil pressure light on. I changed the oil and filter and replaced with 5w-30 (it's gets cold in Ohio) and a mobil 1 oil filter, the clicking got a little better but the low oil pressure light is still on. The car is running old low octane fuel and it's been sitting a while, does it sound like it is indeed a low oil pressure issue or maybe just a bad sensor and dry lifters from sitting. I guess the only way is to screw a mechanical gauge into the oil pressure senor port. Is this as easy as it sounds on this engine? Where exactly is it? Other then that if it really is an oil pressure issue dropping the pan and checking for a plugged pick-up tube is the next step I suspose. Other then that does anyone have any other ideas?