Starting in 1954 Chev did away with the shouldered bolt, you can do the same.
Chev also sold as replacement, rocker supports that had a slot cut horizontally on one side so the supports would clamp down on the shaft. This prevented the shaft from rocking and wearing the supports. I cut a slot on the center support on each shaft to do the same, on the engines I build.
Here is a link to a link to a
Picture.
