here is what i remember on my 327...
a flex fan (at least the one i used) is meant to pull less air at higher rpms - that means that it will flatten out -->i.e. the blades (or ramps) will not be as 'steep'. (air molecules act like the dukes of hazzard and like to jump off of ramps, propelled in the direction and angle that they are pushed)
that means that the outside edge of the BLADES will pull forward slightly at higher rpm. so if it clears the motor and associated parts behind the fan while not running - you are ok.
