Al ,
I had a mates 440 do the same thing . Man it got almost scary hot up to 225 or so .
Anyway .
I tried :
jack up rear of bonnet to help air flow , marginal gain
different waterpump and even pump housing , no change
thermostat and no thermostat , no change
checked the 16" puller electrical fan , nearly blew me over
I was about stumped .
Final resort put an old heavy Mopar fixed 6 blade mechanical fan on it , no shroud .
Could not get the motor to warm up !!
Now as he likes to rev and occasionally race it I put a thermostat in it and a flexlite 7 blade flex fan with a modified Camaro shroud.
Car now runs mid 180's unless a hot day in traffic .
Sometimes the electrical fans simply do not pull enough air no matter the advertising .
Low speed overheat = look at the fan
High speed overheat = look at airflow and coolant flow - radiator condition/size
Over 35MPH airflow should be enough that you don't need a fan .
That airflow can be through the radiator core as well as airflow out of engine bay .
A 3 or 4 core radiator can be as bad as a blocked core for airflow and heat dissipation .
With my sixpack bonnet if I run the air plate on the street the motor runs hotter
Good luck

Tex