Not the level you are discussing, but I like the way the shop that balanced my Callies 4.500" stroke crank did it. Less than 7500 rpm.

The shop said they turned the crankshaft counterweights a lot, so they only have small drill holes for final balance.
They didn’t have to touch the 4 inner counterweights (3.79” radius). They reduced the diameter of the front and rear counterweights about 1/4”; and then only needed one drill hole in the rear counterweight to achieve final balance. About 0.93” dia x 0.66” deep to the tip. They used a drill with a large radius, almost a ball end. They must have gone between the lathe and the balancer a few times to do this. IMO, this leaves more counterweight toward the center of the crank; reducing stress. From my estimates, the Callies crank was over 2500 grams before balancing.


572 CID B1 Build - Part 3. Crank Balance