Been down this road already........I have a set with a single hole and no Banana groove. Used on a hydraulic 340 application. It is quite obvious to me based on the wear pattern on the loaded side of the rocker shaft that a banana groove in this location is a must. I have procured a set of shafts that have 2 oiling holes, one of which has a banana groove in the aforementioned area. Just my opinion, others may disagree.
This response is moot if you are going to used them with solid lifters.
