Educate me on why 340 fan is not symmetrical

Are you using the 70 and up aluminum water pump? Are you installing air conditioning?
The water pump has become a major issue. No AC. Have all the makings for the aluminum pump but the fan shroud I have is for a 68. Looking into swap using pre 70 pump but pulley acquisition has become a problem. Just went through that with aluminum pump. Then there's the issue of the radiator.