If I’m getting what Col Steve is saying, and he can correct me if I’m wrong...all he is doing is moving the feed to the rockers from the feed up from the mains by blocking the hole with the cam bearing and picking the oil up from the lifter gallery.
There is nothing wrong with that, except you are oiling rockers with the oil going to the mains before it gets there. As it is OE, the oil going to the rockers has to at least go to the mains and rods on the way up to the rockers. The OE way only pulls oil off the number 2 and 4 mains, where his way is pulling the oil off all the mains.
I have looked at this at length years ago, but not of a concern for rocker oiling. I didn’t do it, because it still takes oil from the mains. That was when I externally oiled the shafts. In the end that was a giant PITA and not worth the hassles.
I have been looking at other ways to not pull oil from either the mains or before the mains. That would mean any oil going to the mains and rods would have to get their first and the only leaks after the mains would be the leaks at the cam bearings.
I’m not sure how I will do it, but at this point I only see 2 ways to do it. One requires a bulkhead fitting and a couple of hoses and the other requires some hoses off the oil pressure feed port.
I have to consider if it’s even worth the effort, but IMO any time you can feed the rockers with oil that didn’t come off those two mains alone that’s a better way to do it. Not for the sake of the rockers but for the sake of the main and rod bearings.