Fan clutch replacement guidance and recommendations

Are you sure you have the right radiator for that car? If you have the right radiator, has your engine been modified to produce more power that the radiator can handle? It sounds like the radiator is not getting enough air through it to me. Did you modify the grill?
I had my original radiator re-cored by a local shop. It's the 22" unit for V8 LA engines with AC. I have had the cylinders bored 30 over and have a mild cam installed but it's not a crazy hot rod engine by any means. The grille is a brand new factory reproduction by OER