A 302 uses either a 5/8 or a 7/8 belt. If your belt is too narrow, it will slip down into the bottom of the pulley and you never will get it to quit squealing. V belts were made to run on the V. If it has an alternator, it's not original and you may have a narrower pulley on the alternator than the fan and the crank. I would try a 7/8". I think the length is about 46".