I previously ran the car for a couple of hours while monitoring the radiator fans and coolant temperatures. Fans kicked on each temperature spike and never experienced overheating issues at idle so I believe they are in working order. I have also checked to my best ability that coolant flows all the way through so there isn't any blockage.100% agreed here.
OP - I don't understand what you mean by non-coolant related overheating? If the engine is overheating, it has something to do with the cooling system. There is no other failure that would cause general engine overheating without some form of catastrophic local failure i.e. extremely lean condition or retarded timing creates extremely high EGT which can burn valves, turbines, headers, but won't cause "overheating" as defined by coolant temperature.
Head/deck warping, headgasket failure, etc. are the RESULT OF overheating, not the cause. Overheating is caused by either 1. low or no coolant 2. air trapped in the system 3. damaged thermostat 4. coolant passage blockage 5. or damaged radiator or fans
A severely damaged headgasket does introduce air into the system, but you should also notice severe coolant consumption/white smoke during engine operation and almost always significant "yogurt" accumulation in the oil sump.
In regards to severe coolant consumption/white smoke/yogurt like oil, I read online that because MLS gaskets are very strong, they tend to only leak air pockets for a long time until the coolant actually begins leaking into the oil. I have checked the oil multiple times and it always looks good.
Makes me believe that there is an leak from the HG that i've concluded from the dark green block test and also the tiny bubbles I saw in the burp funnel when burping the system.