I think the thing to remember with all these mods is that the recommendations coming from Chrysler or the Larry Atherton book are not to be looked at individually. They are recommended for extreme applications. They are not recommended as to say lets do just this one. They are recommended as an all or nothing because they are interrelated. I have had this oiling discussion many times in the past and there are always non believers of this part or that.
I fail to see why anyone would question Chrysler. They have cast the r3 block with no oiling to the lifters because it was designed as a race block. A race blocks needs it oil path restricted because of the intended usage.
The sbm is not a new engine design. Many racers before us have raced it and can tell you about its oiling issues and how they got it to work. Sanborn was a very successful sbm racer who shared in much detail how he got the engine to live. He too was an engineer.
I had Cometic gaskets design Mls head gaskets for the sbm with the water passages modified to Sanborns design. Anyone on this forum can now buy them. The main bearing problems with sbm are very well documented as are the fixes. But some guys want to do there own thing. To each his own. But my own personal experience with my own engines is that tubing the block and opening the passages works. Restricting the cam bearings works, Reading the article you referenced has confirmed what I thought. Rod bearings oil from centrifugal force, viewing the rod oiling from that perspective makes me realize that opening the main passages to 5/16 and slotting the bearing shells increases the dwell time to get oil into the crank passages.
The higher the rpm, the less time To get it in there. Those passages do not just feed the main bearings, and when the crank passage needs oil, you need to get it there quick.Opening any passage is the easiest way to improve flow and reduce pumping losses.