Looking more and more like an issue with the sender or with the wiring. Started the car up this evening and got 42psi immediately at idle. I don't think the oil pump would have magically healed itself overnight.

Let it warm up and then reved it to 4500-5000. Got 50 psi or so at those RPMs. The gauge seemed to get stuck at 40-50 as it wouldn't go below 40 at idle even with the car at operating temp. The weird thing is that when I turned on my electric fan to keep the car cool it seemed to jar the gauge and it dropped to about 25psi at idle. Definitely something flaky going on. I'll replace the sender and check the wiring.

I'll bring the spare oil pump with me to the track just in case, but I'm going to chalk this up to electrical weirdness. Hopefully that's the case. Thanks for all the help. See you at the track.

David