There are much more radical engines driving on the street nowadays then the Max Wedge engines that were stock.
And they had 2 versions of the 426 Max Wedge. One was 13.5 comp and the other was 11.0 as thats the one they figured people would drive on the street. Both were rated at 425 HP but like was said they made more like 500 HP. Oh and the cam was only .520 lift with about 308 advertised duration. In 64 they dropped the 13.5 eng to 12.5 as they found out it made the same HP. Ron