New Mechanic? All Bs aside, if you destroy and window the number is 273 block then you have issues I had a friend of mine had Joe from Joe's Racing Engines down here taking chunk out of a 440 and repair a windowed 426 Hemi... you ain't going to want to do that with that small block it's not going to be cost-effective. What the fellas are trying to tell you is if you're going to build something that brutal use a different core for a block shelf and save your original number matching book and then you can always return the car back to a numbers matching car.... Dig?