I'm a newbie so be patient.
I just purchased 74 2.0 and drove it home 100+ miles on 98 degree day. Temp gauge got in the 260-280 range but I "made it".

Couple days after, I cranked the car to put it on the lift for a once over and prep for oil change.

After cranking oil pressure reads 80+ and light is on. NO unusual noise. Idles ok
Once I saw pressure was hanging out in the high zone and the light was on I immediately turned it off.

What have I done? What steps to analyze the issue?

FYI,
Once on lift I did find the wire from thermostat was not connected (Per reading, I believe it fails to desired flap position for cooling)

Per PO receipt for most recent oil change using Castrol 20-50 @ 4.8 qts

essentially, 5 quarts is a lot of oil! recheck the oil level in the car while cold and static.

Oil change with filter replacement should get 3.7 quarts....you're overfilled! Definitely check that level out and replace with a high zinc oil like Joe Gibbs Driven, Brad Penn, or Valvoline VR1. Also, check integrity of oil pressure and temp senders, wires, etc.
Not a bad idea to plumb in manual gauges to check out pressure and compare to what your cockpit gauge says....