Do you have an auto trans routed through an internal cooler, do you have a a supplemental cooler in series and where is it located.
I'd try a new thermostat that is tested fir
The pulley situation should be sorted out first.
Flow is important, yet flow can be too fast to effectively cool the water properly.
Is the shroud from the 22" or 24"?
Check the auto trans pan temp for trans temp, and or make sure sender is on correct bung or line (hot area not return) to verify that.