late 50's 235 fan blade should work. Depending on your application... If you are using Patricks S.S. water pump it is sometimes necessary to flatten the fan blade ever so lightly to clear the radiator & harminic balancer . On the other hand it is sometimes necessary to shim the fan blade away from the waterpump pulley & closer to the radiator so the blade clears the harmonc balancer. Use the shortest flatest 4 bladed 235 fan blade you can find & fine tune the temp with the thermostat. If your new 4 core radiator is thicker than the original radiator, it may be tricky getting the fan blade installed without hitting either the radiator or the harmonic balancer.