440 overheating at idle

Looking for some ideas. I have a 71 Dart with a 440 conversion 60 thousand over bore, lumpy cam and 460-500hp. This past winter I replaced the entire cooling system (when I bought the car I thought the car ran hot on occasion). New Cold Case 2 row large tube rad, new water pump, high flow plastic fan, 180 thermostat, has a shroud, new aftermarket temp gauge and it is accurate. The car has no heater, never moves off 180 except at idle in heat (90 degrees+). I haven’t added Water Wetter, but plan to. Car has a vapour lock issue (I plan to insulate the fuel line to correct, it is too hot to touch). Having said all this the only potential issue is the fan spacing. The instructions for the fan calls for placing 3/4” from the rad and it is exactly 3/4”. Having said that the fan is almost completely inside the shroud and I have heard on several occasions that a fan should be 1/2 inside and 1/2 outside. Keep in mind I am mechanically minded and not a mechanic if you come up with some ideas that are extremely complicated. Penny for your thoughts. Ron D