A-Body 440 cooling problem

I guess I am going to keep you guys busy with questions....
The 440 4 speed engine that came in my Duster had an stock 8 blade steel fan. The problem is that the fan pully has 2 grooves and the only one getting the use has only got about a 23% wrap. It squeals like a stuck pig. I tried a clutch fan in it's place and seems to run hot. (26"X18" 3 core, stock)
So....if I go with an alum rad. Do I need the dual fan or single or should I try the ele on the old stock rad. Oh..almost forgot the car does have a complete AC system installed. (not charged yet). Do I need a pusher on it or just hook the rad fan switch to the AC control to bypass the thermostat in hot weather? How many CFM will cool a 440 street car in warm weather with AC.
Also...do you guys run the fan on a thermostat or on with the key?
Bud