There is a big difference between static and dynamic balancing of an engine rotating assembly, and drill holes in crank counterweights are only part of a total balance in reality but this is not a thread for engine balancing and first/second order vibration that occur in four cylinder motor(well mostly second order as first order is nearly canceled)
Wow, cracked outer pump gearotor. That usually happens from a suck OPRV but high rpm cavitation can cause it too.
Good luck on the rebuild 