I grind cranks down from the big, retarded Chrysler Rod throws to BBC (2.375 to 2.200) and small block Chrysler stuff down to SBC SJ (2.125 to 2.000) and never ever found an issue with hardness.
and didnt the folks that do that work for you specialize in that sort of thing? did you ever ask them if they re-hardened it? if they have the means and experience its not that hard to do.