Educate me on why 340 fan is not symmetrical

What size alternator are you going to run and what type of radiator? In my opinion, a fan shroud is mandatory, even if it is home made.
Currently have the single field alternator. Not sure what amperage it is but will work for my initial needs. Have a lead on a 68 340 only radiator #2898026 and same year shroud. This is why I may switch to pre-70 water pump but pulleys are a crap shoot and very expensive. They are advertised for 69 and earlier but will not know until I made another mockup.