To Stroke or not to Stroke?

a local builder i know campaigned a '71 340 Duster that ran 11.5's consistently.He always said it was nothing special just a carefully assembled 340 with Edelbrock heads, a .280 duration cam and 10" slick.. never said what gears.
He tore the engine down in the off season,put a 3.58 stroke rotating assembly in it and changed nothing else.
It ran a best of 10.47 from then on shifting at 7800.Some time later he cracked a cylinder wall and that brings up the question of durability for a stock mopar block at 500 plus hp.