wow, if technology existed that allowed a solid block of cast iron to be forged into an engine block, everyone would be all over it. The strength of the block lies in its design and casting quality. The best thing to do to a stock block would be to add strengthening components to areas that see the highest stress, such as a main cap girdle, or even those lifter valley girdles you can get. The weakest point then becomes the cylinder walls, but as mentioned, a good tune is the key to preventing catastrophic failure.