In one of the SBM books they claim the blocks that were made later, with the 'AC' designation, had holes on the bores. I don't know if that's true or not. But I'm glad mine had none as they say 1/8" holes which would be too big anyway.
The guys who have done lots of W headed engines with pushrod oiling claim it's hard to not over-oil the top end. They also have drain lines running down the outside of the head to the pan to return oil....without them, the W head will hold a lot of oil before it reaches a level that it can drain back through the lifter valley.
If you think about it, the R3 block as shipped will send oil from the #1 main to the the left side galley then the oil does nothing except sit there.