Summer Water Temp Baseline?

You know the thermostat sets the minimum operating temp right? I run a minimum of 205 at the stat-house.
I have found the following to be more than adequate on my 367HO;
With a 7-blade all-steel A/C fan, on a thermostatic clutch, ( It doesn't much care about the shroud or the cowl seal), there should be about a 30degree temp drop between the top and bottom of the rad, idling in your driveway with the hood up.......
Your slanty could probably get away with a 5-blade on a clutch, or a 4 on direct-drive, both with a shroud.
Generally,
the higher the minimum temp, the greater the engine efficiency, and the higher the mpgs will go. The goal is to have a minimum temperature spread between the minimum and the maximum.
The maximum is set by the cooling system efficiency, and that's why I like the thermostatic 7blade fan; it only calls for rotation over a small temp window, and then it freewheels again. But while it's pulling man does it roar.