A bit of experimenting with balancing fan.
I will try it with the pulley attached.
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You look very close there…I would introduce some vibration, though.
Umm… why?
You mentioned having to straighten the blades. If one or two of them had lost some material at the tip due to wearing against some obstacle, at an 8" radius that would significantly affect the balance, much more so than at the radius of the counterweights, and would explain why the original balance marks were no longer valid.
When restoring my Cobra, I managed to source the original type of mechanical fan fitted by SAI when they installed the 289 motors in CA. This was a Mercury Comet item (from memory), and given the revs it was going to do I had it (and a spare) balanced by a fan-balancing company (yes, they do exist!) here in the UK. I had to make up a suitable mandrel for them to spin it on, but an old waterpump shaft did the trick OK. Despite the four-blade sheet steel fan being NOS stock it was quite noticeably out of balance.
Damn you guys, now I’m going to have to take my fan off the ‘S’ and see if it needs balancing before I put the engine in the car 
One thing I learned with the steel bladed fans is that they bend easily. Lay it on a flat surface and make sure all the blades are touching. If on the car, carefully measure the distance from a reference point on the engine to each blade as you rotate the fan.
Pat H
Cheers already made sure they were running fairly accurately in that plane.
I fix a pointer in my magnetic dial gauge stand and spin the fan by hand. Just laying flat is difficult as you can’t be sure the boss is aligned to the flat surface.