another 360/408 over heating

I had the same problems as you. Started with a single electric fan on my 340. Overheated.. went to dual electric and it still overheated.. went to a fan clutch and factory shroud, fixed it..
Put almost the same 408 as you have and figured it was a 340 issue and went back to dual electric fans, overheated.. went back to fan clutch and shroud and barely crack 200 on the hottest days.