It can be done it's just a matter of how long before it cracks. This is what happens when you start pushing an RB block closer to the power needed to run low 9's in a 3200+lb car (my car 3358lbs). This block had a tall fill with hardblock and aluminum main caps. Cracked all the mains into the cylinders on the drivers side of the engine. I would go aftermarket or 400 block with fill, girdle & aluminum caps (I went aftermarket because I didn't want to put all the time and money into another stock block that would probably do the same thing)