The 7 blade setup looks to be from a later year. The factory A/C '65-6 cars I've had used a 7 blade (aluminum blades) fan (2858401) with a clutch (fluid drive). The add-on A/C cars got the 6 blade (all steel) rigid fan w/o a clutch. There was also another A/C fan (2532257) which is shown in my '66 factory parts manual as 7 blade, but, I it should be the 6 blade rigid type. Maybe a typo in my book? They show that being the one with add-on A/C. If that 7 blade you show is the correct diameter, offset and fits without hitting anything, I'd use it. I'd also use the factory shroud too if you have the stock radiator.
