If the pump’s rotating it’s very unlikely to be the problem. Sounds like the radiator’s effectively new, so also unlikely to be the issue.
I hope these aren’t insultingly obvious but if you haven’t already checked them:-
If it hasn’t actually boiled, is the engine really running hot? The temperature gauge may be inaccurate. Try an IR thermometer to confirm the temp on, say, the metal of the thermostat housing.
If it is running hot, is the Kenlowe fan thermostat set to a sensible temperature?
Is the wax thermostat stuck? Try it in a pan of water on the stove (or just swap in a new one). It should be rated at 82C
Have either of the 2 main hoses delaminated internally ; causing a restriction to flow?
If it’s none of these, I guess it could be scale / debris build up in the block(?)
Maybe other Forum members have additional ideas 🙂
