High oil pressure in a 300

So as I stated in the new members introduction thread. I have a 86 F-150 4x4 300 I6 4 speed shortbed. The truck hasn't been driven for about 3 or so years. It was parked because the clutch wasn't working. But as I've been working on it I've started  finding some issues. Not surprised since the truck is 36 years old. I rebuilt the carb, changed the oil and it starts right up. Has a little bit of a miss. But it still runs. But what I've noticed is that the oil pressure gauge goes up very high and pretty much stays there. So where should I start to look. Is it a bad gauge, sensor, oil pump or something else.

Someone may have put an oil pressure switch in when it should be a sending unit. If you have jumper wires you could connect that device to the wire for collar temp, and oil pressure wire to the sender for the coolant temp. The gauges are identical so that way you can test both gauges and sending units.

The only thing I can think is the check ball and spring of the oil pump bypass have become stuck in their seat.
The engine certainly didn't get tighter in 3 years of non use.

It might be interesting to thread an actual mechanical pressure gauge into that sensor port, just to see.

Interesting advice, I actually have a mechanical pressure gauge. It's from my 67 mustang. I'll see if I can make it work. I also forgot to mention that at first startup it has a sticky lifer. But it works itself out after a minute or so.

Using some snake oil like Rislone, Marvel Mystery Oil or even ATF before your next oil change might help free things up.
But high oil pressure (if it actually is that) is turning fluid shearing into heat.

It may simply be the sender.
You can check the resistance.

I run diesel oil specifically because the detergent package keeps dirt in suspension and my engine is clean as a whistle inside.

How do you check the resistance? I have to admit that my weakness in mechanical skills is the electrical side. As well as uploading pictures on this forum lol... Also I use seafoam in all of my other vehicles fuel tanks. I noticed that you can use it as a oil additive. Would this work as well ? I also use diesel oil in this engine.

The oil pressure sender only makes the gauge connect to ground.
10 & 70 ohms at the extremes for Bullnose gauges.

So you can connect a multimeter to ground and the sender with the engine off and see the reading.
Then you can start the truck and see what it's reading.

If you ground the wire going to the sender, the gauge should go to the top of the scale.
But don't do this for any longer than you have to, to avoid damaging the spring in the gauge.