You need to sonic test for sure , and .100 to .125 wall thickness is where you need to be and cross bolting if you re building above 550 hp imo , or maybe a main girdle .. you can buy a garage block from Barry for $ 3500 , it will cost you bout $ 800 - $ 1000 to cross bolt , so maybe look at the long run picture of a 427 block with the stroker kit and get 480 plus inches , or a 428 block at 463 inches .. Bud