Technical Cooling System Problem

You don't have to work that hard to diagnose heater issues, if the hot water goes through the heater core, you got heat, no heat, no flow. One of two reasons, heater core is plugged, or a valve is shut.
Pull the return hose off the water pump, get a bucket first, then fire up the car, aiming the hose to the bucket and see how much water flows through the heater core, simple. No water? Go backward through the system till you find out why.
Forty years of building cars, I've always used a 195 stat, in everything I run, I personally have repaired heating issues in hot rods by upping the T stat to a 195 from either none or a 160 stat, and I'm not gonna be pompous enough to tell anyone why it works, but it does. The biggest heating issue in hot rods is the inability of hot engine air to leave said engine compartment, smooth hood sides, huge engines cramped into small spaces with headers adding to the issue. Wrap the headers, punch some louvers, do what you have to so the engine dissipates (big word) heat. (see, I know them too)
Heater cores are no more than radiators inside your car and the same rules apply to heating and cooling.

 

i remember my shop teacher saying: "all engines are air cooled"
[ok some boats excluded.]