In need of a small block crankshaft pulley

I have a 1968 318 and i want to convert my original 3 belt pulley to a double pulley because i put an aluminum radiator in and my fan wont clear the pulley. Do anyone know where i can get a double crankshaft pulley from. i just wana drive my lil 318 fb cuda until i get enough money to build and stroke my 340. Any info would highly be appreciated Thanks