I am not going to make any friends with this post, but I think it’s accurate for your situation, plus I just don’t care if you like this.
You want answers to why your car is overheating and have given some loose facts for what is going on and what you have tried so far. As you have been quizzed on specific details from members trying to help you narrow down the multitude of variables in your situation to find a cause you immediately go on the defensive as to why that isn’t relevant information to the problem you have. If you want a solution from the brain trust of knowledge at your fingertips you will have to get off your high horse and answer their questions with facts whether you think it is relevant or not.
Such as the actual timing curve you have with an actual timing light. No one is saying you have to change it, but right now it’s something that can’t be ruled out, no matter how much you argue it’s irrelevance… because it’s not rooted in a number, therefore it’s still a potential option. Pull a few plugs and check the color… that’s a question I saw you disregard too, because you ruled out your perfect carb tuning ability. Ok, great, you ruled it out, that doesn’t mean anyone else has. Same with just yanking out the thermostat for a test. If you have done these things great, share that information in a factual way so everyone else can rule it out and move to the next possible cause.
Now, what sticks out to me in this setup you have is that your go to solution was add a bunch of electric fans and because that has “improved” the situation you have grown very attached to these fans. One fact we all know is that from the factory this did not overheat with mechanical fan. So what everyone else has said that has been totally dismissed was that we can’t be sure it’s not restricted air flow on the highway where your RPM overheating issue is occurring. Your immediate response was “they are fine cause they can’t restrict air flow on the back of the radiator” yet that’s not true… a restriction on either side of that radiator is a restriction on that whole section of the radiator.
I have seen others ask about water pump condition. Have you installed a new water pump on it? I get you say you have limited options for high performance water pump, but what about a stock replacement water pump without 9 million miles on it?
Not trying to be mean here, but we are two pages in with a bunch of very experienced and helpful members that want to help you and you still have their attention. But keep dismissing theirs suggestions and questions and you will lose your audience and have to return to solving the overheating on your own… and none of us will feel bad about it.