I'm not a fan of the plastic / nylon tubing - - have to state that right up front.Thanks everyone for your suggestions.....
While your waiting on the new oil pressure gauge to show up, check the tubing to see that neither of the two ferrules have collapsed the tubing and is preventing pressurized oil from acting on the gauge. Also, if you can, try blowing air through the tubing - just to ensure it's free of any debris.
As you've indicated, you can clearly feel the drill rotating in the opposite direction in your hand as you prime the oil circuit so it's definitely building oil pressure. If all the necessary pipe plugs and welch plugs have been installed, then you should have oil pressure.
As for oil filters, if your Fram filter is the HP series, you should be fine. Stay away from the PH series. Wix makes good filters.