Coolant temp differential help

Can someone with an IR temp thermometer do me a favor?

I am curious to see what the temperature differential is between the upper and lower radiator hoses at idle. Please note what type of radiator you have.

I'm just trying to see how much heat should be dissipated under normal operation. My friend is getting a 100+ degree temp difference at idle. His car is running hot on the highway, but not at idle.

My thought is that his radiator is plugged. The restricted flow is keeping the fluid in the radiator for an extended time, allowing it to REALLY cool off. But, the restriction is simultaneously keeping the fluid from transferring heat out of the engine when spinning at highway speed.

He has a 440 with a 3 core 26" factory radiator (In a Belvedere)