Head to any parts house and just ask for a Radiator for a 84 Cutlass with the 307. Or any Gbody with a V-8 for that matter. Glad you know the V-6 Radiator will not hold up. I have made that mistake on my V-8 swaps many years ago. Any other Questions just PM me...I have done 2 V-6 to V-8 swaps. The pic in my sig pic is the latest one.