1966 Barracuda radiator shroud / cooling questions

I ve had flex fans and it seems to me that when thay flex with engine rpm they flatten out. When I first drove my dart 340 solid .528 cam, adjustable rockers, 4 speed , 391sure-grip rear, I had NO over heating problems running no fan. If I were you I d wiggle the fan blades to see if it wiggles, if it does the water pump needs to be looked atand the lower radiator hose with the spring inside does the trick but the spring does rot after a while. My friend had a bad exhaust valve spring creating a overheating like you describe. Just trying to cover some bases, maybe it just would like a cooling system overhaul !!!