Couple of points based on decades of posts re: the fitting:
1. You really really need a set of tube wrenches.
2. Despite your in depth background and details, I'll have to start off presuming you want to replace the line and not the radiator. If it's the orig. radiator, its sidetanks are 25 years old, brittle and often crack by now just looking at them wrong. There is about 79% chance the rubber gasket and/or fitting has broken the seal no matter how carefull the wrenching. If the hose is trash, then saw it off to get a real socket on the end, and tube wrench on the fitting.
3. Now, if replacing the radiator, keep the hose intact and use repeat doses of heat and PB Blaster.
I'm replacing the radiator. I'm going now to get the wrenches and everything else I needed. Can I use my acetylene torch to heat it? I got the fitting to break loose from the radiator but the line itself keeps turning as I'm trying to back the fitting off
The tubing is rusted to the nut. It will be an exercise in patience to get that to come free. Watch out when heating so you don't burn nearby components.
New oil cooler lines are available from RockAuto.