Options are a four blade fan, and one with five blade with a clutch. I used a spacer between fan and water pump pulley. The fan bolted up was too close for comfort to the main pulley. I think its because of the rebuilt water pump depth of the shaft might be incorrect even though it indicates specific to this vehicle. Also, I was using a used fan clutch assembly like that with one with A/C, sourced from another buick with 215.
I have returned to the four blade non clutch fan because I wasn't sure the clutch was performing well. The clutch fan is superior in performance for your engine if you can find one in good working condition. The clutch when heated will stiffen up to blow air through the engine, when cold it is in free play so no air blows to the engine. In comparison the four blade blows all the time. I digress.
Anyways, use a long ruler and look at your alignment with the water pump, pulley and fan fitted. If your fan clears the bottom main pulley when rotating than no spacer needed. If you get a used pulley make sure its not bent in the belt channel or kink in it from being pryed off or your belt will make noises and wear down in that area.