We have a 20 inch 1967 Mustang Steve radiator in The 66.
Upgraded from the 17 inch to the 20 inch wide one for better
cooling. We had to cut 1 1/2 inches from each side of the radiator support to allow air to flow to all of the radiator
Have an electric fan 2500cfm from Speedway that is temperature controlled and run through a relay circuit.
Stainless Steel Radiator overflow/recover tank
The 66 never gets more than 2/3 on the temp scale now even when idling on a hot day.