Mist here would say to run a clutch fan with 6 or 7 blades. Don't see a 4 blade fan much anymore. I run a 7 blade clutch without any issues.
1969 x-77 Z/28 orange/ white stripes, named by my daughter "Clementine ", M-22 close ratio, 4:10 12 bolt, CE 302. Hugger orange with white stripes. White standard interior. Restoration complete May 2018