For what its worth, my stock 68 RS 327 manual 4spd with A/C has a 7 bladed clutch fan unit. They added the clutch fans for A/C cars. My 68 RS/SS 350 with manual 4spd in high school in 1971 had a 4 bladed metal fan with no clutch. At least thats what I remember...
My 67 SS/RS w/350 and powerglide has a four blade fan w/no clutch. But doesn't the water pump dictate what fan you can use. There are long and short snout pumps. My car has a long snout pump with a four blade fan.
1967 Camaro SS/RS 350/295HP Coupe. First and only owner.