There are two different radiator support sizes / openings, you should measure yours. If you are doing a meticulous restoration then stay with the 22; otherwise, if you have the larger opening, I would consider the 26 for extra cooling.
My 71 Cuda was originally a 383 motor and had a 26" radiator. It now has a gen 2 hemi resting between it's 2 front fenders. Make sure by measuring because a 26" rad will keep you cooler.