Conrod bolts are typically high tensile strength steel and are torqued to a preload stress for a certain amount of stretch, but that should be in the elastic range and not cause permanent stretch. For a high performance engine rebuild they are often replaced.
he 350 is a relatively low stress engine though - and not a usual candidate for hotrodding... I've seen several with the bearings replaced, bolts re-used, and not heard of any failures.
