Just for grins, you might try removing your headlight doors. It's just a few fasteners on each. It'll be a lot easier than removing the hood.
I noticed that you have an aftermarket nose. It's possible that its airflow characteristics are just different enough from stock that it's causing issues.
If nothing else, make sure you have an air dam, under the radiator. Something that sticks down ~3 inches should be enough.
(I was troubleshooting an IROC-Z for an old GF. Like yours, it would overheat on the highway. Around town was never an issue. Ended up being a missing air dam, removed after an accident, and never replaced during repairs.)
Beautiful car, by the way.
Edit - I have a Formula with a 4.9. It exhibited a similar issue. This was at 75-80 MPH, with an ambient temperature in the upper 90s. I figured that I was just maxing out the cooling capability of my stock radiator. I also was running "not premium" gas, so that might have made it run a bit hotter, too. (The 4.9 likes premium.)
I also don't have any vents in my hood.
[This message has been edited by Raydar (edited 01-05-2021).]