Another nicely done. How many days to did you think about how to do this? Solutions to problems like this usually come to me after several days, sometimes the solution wakes me up at night.

My dad used to do stuff like that. He would use his father in law's old mike to check for roundness as he filed lawn mower cranks round. Then he filed the caps on the connecting rods and shimmed them with brass shim stock. I used one of those repaired lawnmowers for many years to mow neighbors laws for spending money.