A 10/10 regrind is fairly standard for a first rebuild of a motor, meaning the rod and main journals are both ground down by a mere 0.010" to make sure the rebuild is based on round journals instead of slightly egg shaped due to wear. Above you see that even a 0.020" grind is OK. In bygone years there was a danger that maybe by 0.030" any surface treatment would be removed, but machinists have told me that doesn't matter anymore so I don't know where to draw the line for an unusable crank, but for sure if it only takes a 10/10 regrind that should be as good as new.

Don Shillady
Retired Scientist/teen rodder