The /6 radiator may hold up. A lot depends on the engines output and condition of the radiator. A 2 row will have issues cooling, but could hold up, a 3 row might hold up OK. The larger the radiator the better. So if it is a small /6 unit, you might have trouble. I did a '78, 318 with bolt on parts and a very mild cam. The 2 row /6 radiator worked. Figure the engine probably had approx. 260 HP.
