Replacement factory or O.E. cooling fan?

Hello, How's everyone? I have a cooling fan question?I'm rearin` to get my 68 cuda` back on the road this spring/summer and I practically have everything needed to do so, except I'm having difficulty trying to locate a factory replacement or OE spec cooling fan blade.The car is equipped with a 318 engine and a factory shroud mounted to the radiator(18 inch,6 blade? I'm assuming?).I've seen Advance Auto has a selection of Durale/flexalite fans but was just what you guys/gals recommend as far as where to go to get one or if anyone is using a durale/flexilite fan without issues.I appreciate it.
thanks :)