My OEM 273 shafts (pictured) have 2 holes. I do indeed question if ALL of the 273 mechanical rocker shafts came from the factory that way...maybe 2 BBL models did not? But after 50+ years, who knows what old parts have been mixed and matched.....
If a high lift cam is being used with heavy springs, it is a recipe for failure to not directly oil the pushrod cups. That much has been found out over the years. But, it just takes a dribble for most cases ..... this was designed back in the day when splash oiling was still not that far in the past LOL. Circle track racing (continuous high RPM's) is the worst case I can imagine.
